It takes Jimmy 11 minutes to sweep a porch.
Amy can sweep the same porch in 13
minutes. Find how long it would take them
if they worked together.

5.96 min

Step-by-step explanation:

Jimmy's rate, J = 11 min for whole porch

Amy's rate, A = 13 min for whole porch

to find the combined rate, C,

the reciprocal of the combined rate equals the sum of the reciprocals of each individual rate. i.e

1/C = 1/J + 1/A

substituting the above values

1/C = 1/11 + 1/13  (convert right side to same denominator)

1/C = 13 / (11 x 13)  + 11 / (11 x 13)

1/C = 13 /143 + 11 /143

1/C = (13 + 11) /143

1/C = 24 /143   (taking reciprocal of both sides)

C = 143 / 24 = 5.96 min

8

step-by-step explanation: