Number 10. Please help answer

10) the unshaded part in the figure above is a triangle with

base length = 24 cm
and
height = 12 cm

the area of triangle is given in this formula
A = 1/2 × b × h
A = 1/2 × base × height
A = 1/2 × 24 × 12
A = 144

Hence, the area the unshaded part is 144 cm²

so the answer is (3).