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# Interpreting linear functions — Harder example

Watch Sal work through a harder Interpreting linear functions problem.

## Want to join the conversation?

• couldn't khan cut the mistake in through .
• I almost find it comforting that a teacher might also make a mistake; as long as he corrects it in the end!
• At , how do we know what "15" stands for? This video had me confused. Why do we try to find the mystery unit? Do we treat "32" as we would the variable "x"?
• It's because the equation is Gallons = 15 - miles/32. If the miles equal zero, it means the tank is full. So the equation would be Gallons = 15 - 0/32. Gallons = 15 - 0. Therefore, a full tank of gas holds 15 gallons.
• The whole miles per gallon thingy is a bit confusing......... Can anybody explain further to me.....thanks
• Miles per gallon means a total number of miles you can travel using a certain amount of gallons of fuel. For example if your miles per gallon 5, that means, with 1 gallon of gas, you go 5 miles. So 5 miles per 1 gallon.
If your miles per gallon 20, that means, with 1 gallon of gas, you go 20 miles.
So 20 miles per 1 gallon.
Hope this helps.
• hi i am aware that the 3 rd option is very confusing. Let me explain. So basically a tank of gas may have the same units which are gallons but be careful here because when they mention a tank of gas, they always are talking about the value 15 gallons as default. Hence if you pick the third one , you will basically be saying that solution is( miles/15 gallons). Hope this helps
• at why did he take the reciprocal of both sides?
• In order to isolate the "units", he must switch out the co-existing variable on the left side.
• In the question about the gas tank (Interpreting linear functions - Harder example), don't we have to say "Alice's car can travel 32 miles per gallon" instead of "to the gallon"? I'm not a fluent English speaker, but I don't recall hearing such a way to say it.
• Honestly, I've grown up hearing it both ways. They're practically interchangeable- it just depends on where you live. You don't have to say it ("per gallon" might make more sense for some people), but in the end, it's the same.
• I am confused when solving the practice questions, because the explanations to the answers are different than the videos provided. The practice questions solve by using a slope? Im lost.
• Can someone please explain to me why it is that he multiplied by miles SPECIFICALLY?
• Because he wanted to cut out the miles from the denominator.