Can someone me understand how to do this ?

I'll do the first two.

1.

Just use sine. Sine is equal to Opposite/Hypotenuse.

sin(x) = 24/40

Find the inverse sin of both sides:

x ≈ 36.90°

2.

You only know the side opposite and the side adjacent to angle M, so use tangent.

tan(x) = 27/36

Take the inverse of tangent of both sides:

x ≈ 36.90°

Just divide the x axis (the top) by 2 or multiply the y axis (the bottom) by 2

A) 144.44 sq inches i believe