So, the area of a parallelogram is the base times the height or

a being area
b being base
h being height
the height is 8 cm and the base is 15 cm
(remember: the heght should be perpendicular to the base)
so we plug in 8 for h and 15 for b to get

and 15 × 8 = (10 × 8) + (5 × 8) = 80 + 40 =120
So the answer is 120