Explanation:
Technically, you can work without the area of the square considering that you only need the triangles area. In order, to find the triangles area, you need to multiply the base times the height then divide by two. The area of the triangle equals to half of the sum of base times the height or:
A of Triangle = 1/2 bh
So, in this problem, b equals 13 and h equals 6 1/2 which can be converted to 6.5.
13 x 6.5 = 84.5
84.5 divided by 2 = 42.25
42.25 converted into a fraction is 169/4, but your answer box seems to be for a whole number; not a fraction.
So for triangles, remember:
A = 1/2 bh
And for the rectangle in this equation:
H: 6 1/2
W: 13
6 1/2 x 13 = 169/2 or 84 1/2
Just remember A (Area) = h (height) x w (width)