Find the area of the entire shape and the area of just region A, then divide.
Entire area = 9 x 10 (5+4 x 3+3+4) = 90 square inches.
Area of Region A = 5 x 7 = 35 square inches.
The probability becomes 35/90, which reduces to 7/18.
You don't state if the answer should be a fraction, decimal or percent so I have all three listed below:
As a fraction: 7/18
As a decimal: 0.39
As a percent: 38.9% (rounded to the nearest tenth or 39% rounded to the nearest whole number.
