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the price of a visit to the dentist is $50 if the dentist fills any cavities an additional charge of $100 per cavity gets added to the bill if the dentist finds n cavities what will the cost of the visit be write your answer as an expression all right so we're talking about the cost of the visit so you're going to spend $50 no matter what and then you're going to get and then you're getting an additional charge of $100 per caddy they tell us an additional charge of $100 per cavity so let's see if you have n cavities it's going to be $100 times n 100 I could just write this as a hundred n let's see if this makes sense if you have no cavities if n is zero then you're just going to pay your $50 but if you have one cavity you're gonna pay your $50 plus 100 times one if you have two cavities you're gonna pay $50 plus 100 times two yeah this seems to make sense so let's check our answer we got it right let's do another one of these Sonny earns $12 per hour delivering cakes she worked for X hours this week she worked for X hours this week unfortunately she was charged $15 for late delivery on Tuesday how much money did Sonny earn this week so if you see that she earns $12 per hour and she worked for X hours it's okay she got $12 per hour times X hours so that's how much she would have made except for the fact that she also had she was charged I guess her employer charges her for late delivery so she had to take $15 out of her paycheck so this is what she would have gotten paid based on her hourly wage and the number of hours she worked but then she has that late fee that she has to pay so it's going to be 12x minus 15 is how much she actually earned this week let's do let's do a few more of these there are C players on the Cougar on the Cougars hockey team the team scored a total of 36 goals this season one of the players Mathieu scored two more goals than the average per player how many goals did Matthew score alright well let's think about the average per player because we know he scored two more than the average lair so the average is going to be the total number of goals divided by the number of players and they tell us there's C players so this this expression right over here that would tell us the average that that's the that's the average goals per player now we know Mathieu scored two more than this thing over here so we can just add two to that and that's how many goals Mathieu scores let's check our answer and the key here this might seem a little confusing but remember this has Mathieu scored two more goals two more goals than the average player the average player the average goals per player is 36 divided by C let's do let's do one more of these Hannah has 127 books in her collection her school is hosting a book donation there are Z students at her school and they each plan to donate the same amount of books and reach a total donation of 300 books how many books will well Hannah have in her collection after her donation all right so let's let's think about Hannah has 127 books in her collection that's how much she has in her collection her school is hosting a book donation there Z students at her school and they each plan to donate the same amount of books and reach a total of 300 books how many books will Hannah have in her collection after her donation so 127 and I don't just reread it cuz at first I was like okay wait is 127 the amount of books that Hannah has or the amount that her school has we'd be very clear 127 is the number of books Hannah has then she's going to donate some of those books so she's going to donate some of those books to her school and we have to figure out how much is she going to donate to her school and we see that the students the Z students plan on together and they each want to donate the same number of books and together they're going to donate 300 books so e how much is each student going to donate well if they're if they're if Z students together are donating 300 each student is going to donate 300 divided by Z 300 divided by Z and so Hannah starts with 127 books she's going to donate her share of books to the school and each student is going to donate three hundred divided by Z books so Hana is going to be left with 127 minus 300 over Z books after her donation