Civil engineering formula

Civil engineers use the formula Q = 3.32LH^3/2

to find the maximum discharge that the dam (a broad-crested weir) shown in

the figure can pass before the water breaches its abutments (Standard

Handbook for Civil Engineers, 1968). In the formula Q is the discharge in

cubic feet per second, L is the length of the spillway in feet, and H is

the depth of the spillway. Find Q given that L=60 feet and H=5 feet. Find H

given that Q=3000 cubic feet per second and 70 feet.

This is what I have come up with thus far.

Q = 3.32*60*5^3/2

Q = 12450

3000 = 3.32*70H^3/2

L = 2.95555