Which system of inequalities can miss robinson used to find a, the number of chairs with arms, and w, the number of chairs without arms, that she can buy?

We know that 80a + 70w ≤ 7500 because Ms. Robinson cant spend more than 7500, so the answer must be A or D.

We also know that a + w ≥ 100 because Ms. Robinson must buy at least 100 chairs.

This leaves our answer to be A 

A=bxh3.2x1.8=5.76 centimeters square