Question

Betsy and Mary both got their hair cut on the same day. Betsy gets her hair cut every 28 days, and Mary gets her hair cut every 35 days. How many days will it be until they both get their hair cut on the same day again?

Answer 1

"Betsy gets her hair cut every 28 days and Mary gets hers every 35 days"
Find the least common multiple of 28 and 35.

28 = 2²×7
35 = 5×7
LCM(28, 35) = 2²×5×7
= 140