a new machne can make 10000 cns three times fster than an older machine. with both machines working, 10000cans be made in 9 hours. how long would it take the new machine, working alone, to make the 10000 cans

Question

anonymous · Answer

let old machine take x hours
then new takes x/3 hours

working together they take 9 hours

so            x * (x/3)
                --------   = 9
                 x  + x/3

 x^2 / 3    = 9 *  4x / 3
3 x^2  = 108x
x^2 = 36 x
x ^2 - 36x = 0
x = 0 or  36

new ,achine takes 36 / 3 = 12 hours to make 10000 cans