A shoe repairman is working with his assistant, who takes 1.5 times as long to repair a pair of shoes. Together they can fix 10 pairs of shoes in six hours. How long does it take the repairman to fix one pair
of shoes by himself?

1/2 or 0.5 hours

Step-by-step explanation:

r = time for repairman to fix one pair of shoes.

a = time for assistant to fix one pair of shoes.

a = r×1.5

x×r + y×a = 6

x = number of pairs of shoes repaired by repairman.

y = number of pairs of shoes repaired by assistant.

x+y = 10

y = 10-x

x = y×1.5 (based on the a/r ratio : as the assistant needs 1.5 times longer, the repairman will have repaired 1.5 times more pair of shoes in the same time)

y = 10 - y×1.5

y + y×1.5 = 10

2.5×y = 10

y = 4

=> x = 6

6×r + 4×r×1.5 = 6

6×r + 6×r = 6

12×r = 6

r = 6/12 = 1/2 or 0.5 hours

its 4 because 2 times 2 is 4, if you double the number two you get four