Please answer the following question by reasoning step-by-step.
If one fourth of the engines are defective, and there are 5 batches of 80 engines each. How many engines are not defective?

300
There are 80 * 5 = 400 engines in total.

400 / 4 = 100 of the engines are defective.

400 - 100 = 300 of the engines are not defective.

.

So, the answer is 300