A - number of lawn that Tim needs to mow
310 < 120 + 30a
190 < 30a
6.333 < a
a > 6.333
Tim needs to mow at least 7 lawns in order to earn more than $310
6 can go into 70 11 times without having a remainder so the 11 goes on the outside as your whole number. Then you have 4 left over to get to 70 so 4 becomes your numerator. The 6 stays as your denominator. So you have
Your answer will be about 11.