Question

Wade can paint a certain room in 7 hours. Rhonda can paint the same room in 5 hours. How long will it take them working together to paint the room? Round your answer to the nearest hundredth if necessary.

PLEASE come up with a rational expression to solve this problem. 

Answer 1

Wade can paint a room in 7hr. So in 1 hour she can paint 1/7 of room
Similarly Rhonda can paint 1/5 of room in 1 hour

Let x be the number of hour required if they work together
1/7 + 1/5 = 1/x
=> (5+ 7)/35 = 1/x
x= 35/12
= 2.91

i.e around 3hrs will be required to paint the room together