I'm struggling with this question. Could someone please help me?

Answer:
(5x+2)(3x-1)-x(x+7)= A
Step-by-step explanation:
use (5x+2)(3x-1)... then subtract x(x+7) from it soooooo
because once you get the area of the big shaded rectangle (with the white rectangle inside) you have to subtract the white triangles area to find the shaded one's