Question

jo has swimming lessons every 3 days and violin lessons every 7 days.how many days would it take to have both lessons on the same day?

Answer 1

21 days

Answer 2

every 21 days

Answer 3

LCM of 3 and 7 is 21. So it takes 21 days to have both lessons on the same day.

Answer 4

just look at the tables of 3 and 7
3, 6, 9, 12, 15, 18, 21, 24, 27, 30, .......
7, 14, 21, 28, 35, 42, .............................

Their least common multiple is 21

so after every 21 days

Answer 5

7*3=21