Joe has a collection of 14 coins that are quarters and dimes, if he has x dimes, how many quarters will he have to have more than $2.20

Question

In 7th acc math

Answer 1

There are 14-x quarters worth 25(14-x) cents, the dimes are worth 10x cents.

25(14-x)+10x>220.

350-25x+10x>220, 130>15x, so x<130/15, x<26/3, x≤8, and or -8≤-x and 14-8≤14-x, 6≤14-x.

Therefore he needs 6 or more quarters (and 8 or fewer dimes).