Answer:
length = 20 cm and width = 8 cm
Explanation:
l  - length
w - width
length and width are in a ratio of 5:2
 cross multiply
 cross multiply
 divide both sides by 2
 divide both sides by 2

the area is 160cm²

We have the system of equations:

Substitute (1) to (2):

Put the value of w to (1):
