Formula
The area of any triangle is
A = 1/2 * b * h
Givens
A = 10
b = 4
h = x + 3
Sub and solve
10 = 1/2 * 4 * (x + 3) Take 1/2 of 4
10 = 2 * (x + 3) Divide by 2
10/2 = 2( x + 3) / 2
5 = x + 3 Subtract 3 from both sides.
5 - 3 = x + 3 - 3
2 = x <<<<<<<<<<<<<< answer.