Question

What is the value of x?

A. 5
B. 2.5
C. 7.5
D. 10

Answer 1

The two lines are horizontal, so the two triangles in the diagram are similar because their internal angles are the same. By the proportionality of similar triangles, x/(x+5)=(x-2)/(x+1). Solve the equation, x^2+x=x^2+3x-10, x=3x-10, x=5.