I’m not sure how to find Area.

B) 99 square meters

Solution:
Area = (base)x(height)

1st method:
—pretend you are finding the area of a big parallelogram where height is given 12m. The base is 4m+5m+3m=12m
—Area=(base)x(height)=(12)(12)=144square meters
—Find the area of the small dimensions or rectangles;
area=(base)x(height)=(4)(5)=20square meters
area=(base)x(height)=(5)(5)=25square meters
—Subtract the area of small dimensions from the total dimension which is 144 square meters; 144-20-25= 99 square meters

2nd method:
—Split the two dimensional figures to three rectangles and determine the area of each rectangles;
area=(base)x(height)=(12)(4)=48square meters
area=(base)x(height)=(12)(3)=36square meters
12m-4m-5m=3m
area=(base)x(height)=(3)(5)=15 square meters
—Add up the areas of the three rectangles;
(48+36+15) = 99 square meters

The answer simplified would be. -6300x