Question

Tina can paint a room in 8 hours, but when she and her her friend Emily work together, they can complete the job in 3 hours. How long would it take Emily to paint the room alone?

Answer 1

T can paint a room in 8 hrs, Thus in 1 nr T can paint 1/8th of the room
T+ E can paint a room in 3 hrs, thus in 1 hr T + E can paint 1/3 rd of the room

Thus E alone, in one hour can paint 1/3-1/8 of the room = 5/24 th of the room

Thus E will need 24/5 hours to paint the whole room alone = 4.8 hrs