Area of a triangle is 1/2 x base x height.
base = 12
Height = x+6
Area = 1/2 * 12 * x+6
Area = 1/2 * 12x * 72
Area = 6x + 36
Perimeter is the sum of the 3 sides:
x-7 + 12 + 2x+5
3x -2 + 12
3x+10
The last choice is the correct answer.
