Answer:
x is equal to 27
Step-by-step explanation:
To find this, start by making a proportion. In order to do so, you need to set it up using the smaller triangle on the right and the larger triangle on the left.
39/x = 65/(x + 18)
Now cross multiply to solve.
65*x = 39(x + 18)
65x = 39x + 702
26x = 702
x = 27
