Did you use your scale that 1/4 inch equals 40 feet?.

b1: How many 1/2 inches are in 3.5 inches?. 7

7*40=280

b2: How many half inches are in 5 inches?. 10

10*40=400

Proceed in that fashion and you should be OK. It's like that other problem I stepped through involving scales.

Find the square feet form this and then divide by 43,560 to find the acres.