Answer:
400yd^2
Explanation:
since the length is 4 times the width, let's call it 4w, and since theres 2 lengths and 2 widths, ima start out by adding a 2 before the variables in the following algebraic expression
2(4w)+2w=100yd
8w+2w=100yd
10w=100yd
w=10yd
now, we know that the length is 40 because that's 4 times 10
length times width is area, so
40yd x 10yd
400yd squared