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Current time:0:00Total duration:4:20

Interpreting two-variable inequalities word problem

CCSS.Math:

Video transcript

Goku wants to get over 9000 comments on his YouTube videos he gets the same number of comments for each cat video that he uploads and he gets the same number of comments for each dog video that he uploads that's somewhat amazing then you have the exact same number of comments for each cat video and the exact same number for each dog video but we'll just assume what they're telling us in the following inequality si represents the number of cat videos C for cat and D represents the number of dog videos D for dog dog videos that goq that Goku should upload to achieve his goal so 750 times the number of cat videos plus 450 times the number of dog videos needs to be greater than 9000 according to the inequality how many comments does each cat video get and how many comments does each dog video get so let's see if we understand what's going over here what's going on in this inequality to answer their question so he wants to get over 9000 comments and we see that right over here he wants to get over 9000 comments so this we could view as a number of comments that he actually gets and since we have some number times C we could assume that we'll see well we know that C is the number of cat videos and so the number times C that's the number of comments that he gets from cat videos and on a per cat video basis he's going to get 750 comments because if I say hey look I have C cat videos on each of them I have exactly 750 comments well I'm going to have 750 times C comments on all of my cat videos combined so each cat video gets 750 comments and similarly I can never say that each dog video gets well this is the total number of comments from dog videos you add all of this together your total number of comments which need to be greater than 9000 well if the total from dog videos is 450 D that means he's getting 450 comments per dog video 450 comments per video times the number of dog videos gets the total comments from dog videos so he gets 450 comments per dog video can go to achieve this goal by uploading 8 cat videos and 7 dog videos so let's think about this 8 cat videos 7 dog videos so let's see if we have 750 let me do those same colors if we have 750 times 8 times 8 plus plus 450 times 7 is this greater than I'll write it as a question mark because we don't know is this going to be greater than 9 9000 well we just have to evaluate this what is this going to be let's see 700 times eight is fifty-six hundred it's going to be 5,600 plus another 50 times eight is 400 so 5,600 plus 400 is sixty hundred or six thousand so this is 6 this is six thousand right over here so that would be if you has eight cat videos you get 750 comments per video so it's going to have a total of six thousand comments on all of the eight cat videos combined and then 450 times seven let's see four hundred times seven is twenty-eight hundred plus another thirty plus another 350 that's going to be what 30 150 is that right let's see that would be let me make sure I do this right 28 hundred plus 24 hundred times seven is twenty-eight hundred fifty times seven is three hundred fifty yep I think that is right it all all works out 30 150 so 6000 plus 30 150 is indeed greater than 9000 it is indeed greater than 9000 this over here is 9000 150 which is indeed greater than 9000 so yes he can achieve his goal by uploading eight cat videos and seven dog videos