Together, Bob and Tom take 4 hours to get the yard work done. If Bob works alone, it takes him 6 hours. How long would it take Tom, working alone, to do all of the yard work?
The answer is 12 and let me tell you how can you get to that conclussion: Let X be the number of hrs Tom takes to do it Add their rates of working ( 1 yard ) / ( 6 hrs ) + ( 1 yard ) / ( X hrs ) = ( 1 yard ) / (4 hrs ) and then what you do is 1/6 + 1/x = 1/4 Remember to multiply both sides by 12x then = 2x + 12 = 3x
