Mark has 3 tanks for pregnant fish. Each tank has 4 pregnant fish and each fish gives birth to 20 young. How many young fish does he have at the end?
Please answer the following question by reasoning step-by-step.
240
He has 4 * 3 = 12 pregnant fish.

They give birth to 12 * 20 = 240 fish.

.

Thus, the answer is 240