Answer:
64
Step-by-step explanation:
Let the missing side be " x "
30 / ( 30 + 10 ) = 48 / x.
30 / 40 = 48 / x
3 / 4 = 48 / x
3 * x = 4 * 48
x = 4 * 48 / 3
= 4 * 16
x = 64