Question

At Alan's auto shop, it takes 15 minutes to do an oil change and 7 minutes to do a tire change. Alan has less than 1.5 hours ( 90minutes) left to work before he has to leave for the day. Write an inequality that gives the number of oil changes, x, and the number of tire changes, y, that he can do before he leaves.

Answer 1

ok so this is algebra problem:

let say that the number of oil changes is x and the number of tire changes is y:

each oil change takes 15 minutes, so 15*x will be the time he spends on oil changes
each tire change takes 7 minutes, so 7*y will be the time he spends on tire changes

the total time that he has is 90 minutes
when we combine these:

15*x + 7*y has to be less than or equal to 90 minutes