Take into account the area of the three parts of the figure.
There are two equal triangles, their areas are:
A1 = b·h/2 = (3 ft)(4 ft)/2 = 6 ft²
A2 = 6 ft²
The area of the rectangle is:
A3 = w·l = (10 ft)(3 ft) = 30 ft²
The area of the total figure is:
AT = A1 + A2 + A3
AT = 6 ft² + 6 ft² + 30 ft²
AT = 42 ft²
