Rectangle A has 7 times the area of rectangle

b. The width of rectangle A is half the width of rectangle

b. The height of rectangle A is 20mm. Wat is the height of rectangle

b.

Wa=0.5Wb, Ha=20, Hb is unkown

the area of rectangle a is : Wa*20

the area of rectangle b is : Wb*Hb

Rectangle a has 7 times the area of rectangle b: Wa*20=7*Wb*Hb

Replace Wa with 0.5Wb: 0.5Wb*20=7Wb*Hb = > Hb=10/7