Question

sam can mow his yard in 5 hours. Lucy can mow the same yard in 3.5 hours. How long will it take them to mow the lawn together?

Answer 1

Sam workrate 1/5

Lucy workrate 1/3.5 = reciprocal of 7/2 = 2/7

combined workrate: 1/5 + 2/7 = 17/35

they will mow the lawn in 35/17 = 2 and 1/17 hours

2 hours 3 1/2 mins

Explanation: