Very simple algebra problem, please help!?

jason

One guy can paint a house in 6 hours. The other guy can paint it in 4 hours. How long will it take to paint a house if they work together?

This seems very simple but I just can't get it.

daisy-marshall_609bf9803c362

1st guy has painting work rate 1/6 houses per hour

2nd guy has painting work rate 1/4 houses per hour

If we denote the time taken to paint the house x hours and set the number of houses as 1

Use formula: painting rate (houses/hr) x time taken (hrs) = number of houses painted (houses)

for 1st guy: 1/6*x=1 ----> x=6 hours

for 2nd guy: 1/4*x=1 ----> x=4 hours

together: 1/6*x +1/4*x =5/12*x ----> x=12/5 hours

x=2.4 hours

rameshwar

let guy is A & B

A's work of 1 hour = 1/6

B's -----------------------= 1/4

both together in 1 hour paints = 1/6+1/4 = 10/24

so total work by both together in = 24/10 = 2.4 hours

i.e. in 2 hour & 24 minutes ANSWER