It takes Jay, Elle and Kay to work individually for 70 minutes, 105 minutes and 52.5 minutes respectively
A ratio can sometimes be regarded as fraction. While rate has something to do with time.
Given that Jay and Kay can pack the shelves in one aisle of the supermarket in 30 minutes. Kay and Elle take 35 minutes to do the same job. When Jay and Elle work together, the job takes 42 minutes.
Let
The interpretation of the question go thus;
1/J + 1/K = 1/30 ........ (1)
1/K + 1/E = 1/35 .........(2)
1/J + 1/E = 1/42 .........(3)
Make 1/J and 1/E the subject of formula in equation 1 and 2 respectively and substitute them in equation 3
1/J = 1/30 - 1/K ........ (4)
1/E = 1/35 - 1/K .........(5)
1/30 - 1/K + 1/35 - 1/K = 1/42
Collect the like terms
- 1/K - 1/K = 1/42 - 1/30 - 1/35
-2/K = (35 - 49 - 42)/1470
-2/K = -56/1470
1/K = 28/1470
Reciprocate both sides
K = 1470/28
K = 52.5 minutes.
Substitute K in both equation 4 and 5
1/J = 1/30 - 28/1470
1/J = (49 - 28)/1470
1/J = 21/1470
Reciprocate both sides
J = 1470/21
J = 70 minutes
1/E = 1/35 - 28/1470
1/E = (42 - 28)/1470
1/E = 14/1470
Reciprocate both sides
E = 1470/14
E = 105 minutes
Therefore, it takes Jay, Elle and Kay to work individually for 70 minutes, 105 minutes and 52.5 minutes respectively
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