Working together, Tim and Jeff can detail a car in 2.5 hours.
Working alone, Tim can detail the same car in 4.5 hours.
Approximately how long will it take Jeff to detail the car if he is working alone?

Question

anonymous · Answer

Time together      Time together
------------ +  -----------  = 1
Time alone           Time alone

Generic equation

anonymous · Answer

2.5         2.5
--    +    ---   = 1
4.5           x


Multiply by common denominator of 4.5x

anonymous · Answer

4.5x(2.5)         4.5x(2.5)
--------   +   -------- =   4.5x(1)
    4.5                    x

anonymous · Answer

Cancel the denominators into the numerators

anonymous · Answer

x(2.5) + 4.5(2.5) = 4.5x(1)

anonymous · Answer

2.5x + 11.25 = 4.5x

anonymous · Answer

Solve.
2.5x + 11.25 = 4.5x
11.25 = 2x
5.625 hours

anonymous · Answer

wow..thanks.