Q. 1

It takes 8hr for 5 people to paint a room. How much time does it takes with 4 people?

$8hr \rightarrow 5 \, people 5 \, people \rightarrow 8hr 1 \, people \rightarrow 8 \times 5 4 \, people \rightarrow 40 \div 4 \Rightarrow 10 hr$