how to do this ?? help

Answer:
45 cm²
Step-by-step explanation:
The area of the shaded region is calculated as
area of outer triangle - area of inner triangle
area of outer = [tex]\frac{1}{2}[/tex] bh ( b is the base and h the height ) , then
A = [tex]\frac{1}{2}[/tex] × 15 × 10 = 75 cm²
area of inner = [tex]\frac{1}{2}[/tex] × 12 × 5 = 30 cm²
Thus
area of shaded region = 75 - 30 = 45 cm²