Answer:
x = 28
Step-by-step explanation:
We can use ratios to solve
x x+10
------ = -----------
42 42+15
Using cross products
42(x+10) = x(42+15)
42x+420 = 57x
Subtract 42x from each side
420 = 15x
Divide by 15
420/15 = x
28 =x
