The shape consists of a rectangle on the bottom and a trapezoid on the top.
Rectangle
A rectangle has a very simple Area formula. It is Area = L*W. In this case the L = 14 m and is horizontal. The width is at right angles to the length and is marked as 3.
Area = L * w
L = 14
w = 3
Area = 14 * 3 = 42 m^2
Trapezoid
The trapezoid is a bit more complicated and some things have to be found. First of all b1 is the first base of the trapezoid. It is parallel to and equal to the Length of the rectangle. b2 is marked 10 meters. The height is just a bit more complicated. The total height of the figure is 8 m. You can't count the 3 m of the rectangle as part of the height because b1 comes only to the top of the rectangle. The height is 8 - 3 = 5
To find the value of a, use the area formula for a triangle. The formula is A = 1/2 *b*h. Here b = x and h= x. The formula becomes A = 1/2 *x². Substitute A = 53 and solve for x by using inverse operations.
