Answer:
length = 16m
width = 4m
Explanation:
1. if the length is 4 times the size of the width then we can call the width x and the length is 4x
2. make an equation 4x + 4x + x + x = 40m
3. solve the equation 10x = 40 x = 4
4. width = x width = 4m length = 4x length = 16m
5. check this 16 + 16 + 4 + 4 = 40