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Mathematics 20 Online
OpenStudy (anonymous):

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?

OpenStudy (anonymous):

21 days

OpenStudy (anonymous):

every 21 days

OpenStudy (kira_yamato):

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

OpenStudy (anonymous):

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

OpenStudy (anonymous):

7*3=21

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