Question

For the figure below, if the two triangles are congruent and the side AC = 2x - 4 and side DF = x + 5, what is the value of x?

Answer 1

Remember that

If two figures are congruent, then their corresponding sides are congruent

so

In this problem

The given triangles are congruent

and

AC and DF are corresponding sides

therefore

AC=DF

substitute given values

2x-4=x+5

solve for x

2x-x=5+4

x=9

The answer is option C