Try this solution, it consists of two parts (MN=8).
Selling 90 would reach her goal of $135 so she would need to sell 91 to exceed her goal
135/1.5=90 so 91*1.5=136.5
The equation in the question is not the same as the one in the picture so here's the answers to both of them.
Q1 - 1/3 or 0.333333
Q2 - 1/108 or 0.009259
Make them common denominators