Answer:
x =5
Step-by-step explanation:
We can use ratios for the side lengths
9 x
--------- = -----------
9+18 x+10
Using cross products
9 (x+10) = x * (9+18)
Distribute
9x+90 = x*27
9x+90 = 27x
Subtract 9x from each side
9x-9x+90 = 27x-9x
90 = 18x
Divide each side by 18
90/18 = 18x/18
5 =x
