For every white duck at the lake there are 5 fish. For every black duck there are 10 fish and for every multicolor duck there are 12 fish. Currently there are 3 white ducks, 7 black ducks and 6 multicolored ducks. How many fish are in the lake?
Thoughts? Step-by-step reasoning:
For every white duck there are 5 fish and there are 3 white ducks for a total of 5 * 3 = 15 fish. For every black duck there are 10 fish and there are 7 black ducks for a total of 10 * 7 = 70 fish. For every multicolored duck there are 12 fish and there are 6 multicolored ducks for a total of 12 * 6 = 72 fish. All total there are 15 + 70 + 72 = 157 fish in the lake.
Thus, the answer is 157.