Question

if they do not act fast,they will fail (turn into an affirmative sentence​

Answer 1

they do not act fast then they will fail

Answer 2

Hey mate answer of your question is given below by me.

Explanation:

Negative Sentence:

If they do not act fast, they will fail.

Affirmative Sentence:

If they do act fast, they will pass.

I hope it can help you....