Add punctuation: By these evils a third part of men was put to death by the fire and the smoke and the burning smell which came out of their mouths
A: By these evils a third part of men was put to death, by the fire, and the smoke, and the burning smell which came out of their mouths.

Add punctuation: Healthy and happy employees would mean more productivity energy and positivity at the workplace
A: Healthy and happy employees would mean more productivity, energy and positivity at the workplace.

Add punctuation: If you need customer service assistance then contact us 7 8 9
A:
a If you need customer service assistance, then contact us. 7 8 9