If you know the rest to geometry b unit 3 lesson 5 proportions in triangles

The value of x is 5.

To solve this problem, you have to write a proportion to solve for x. The segment on the left and right of the triangle are proportional because the lines are parallel.

So our equation is:

x/(x + 5) = (x - 2)/(x + 1)  Cross multiply
x^2 + x = x^2 + 3x - 10    Cancel off the x^2
x = 3x - 10                       Subtraction 3x from each side
-2x = -20                          Divide by -2
x = 5

What am i doing here. add?