Question

carl goes to the beach every third day and antonia goes every seventh day. how often do they see each other?

Answer 1

Carl and Antonia see other after every 21 days or after every three weeks.

Explanation:

i) Carl goes to the beach every third day.

ii) Antonia goes to the beach every seventh day.

iii) the lowest common multiple of 3 and 7 is LCM(3,7) = 3
`*` 7 = 21

iv) therefore Carl and Antonia see other after every 21 days or after every three weeks.