General Mathematics

Question

Bia can wallpaper a roon in 4 hours and her brother can do it in 6 hours. How long would it take them if they work together?

Answer 1

1/4 + 1/6 = 1/T

multiply by 12T to eliminate fractions

3T + 2T = 12

5T = 12

T = 12/5 = 2.4 hours if they work together, and don't get in each others' way