Area of parallelogram = base * height
base 1 = 4.2 cm
height 1 = 3.6 cm
∴ Area = 4.2 * 3.6 = 15.12
let the other base 2 = x
∴ the altitude of this base = height 2 = 2.4
∴Area = 2.4 x = 15.12
Solve for x
∴ x = 6.3 cm
∴ The perimeter of parallelogram = 2( base 1 + base 2)
= 2 ( 4.2 + 6.3 ) = 21 cm