Question 234370
 
Sally can paint a house in 4 hrs so her rate is 1/4 (1/4 of the house will be painted in one hr), and 
Joh can paint house in 6 hrs , his rate is 1/6

In x hours, Sally paints  x/4 of the room and John paints  x/6 of the room. Since they will be working together, we will add the two parts together. The sum equals one complete job and gives us the following equation: 
{{{(x/4)+(x/6)=1}}}
solving for x:
3x/12+2x/12=1
5x/12=1
5x=12
x=12/5
x=2 2/5   2hr 24mins