SOLUTION: Two vacationing families leave San Francisco at the same time. They take 28 and 6 days, respectively, to reach their destination and return to San Francisco. The vacationing famili

Question 1175834: Two vacationing families leave San Francisco at the same time. They take 28 and 6 days, respectively, to reach their destination and return to San Francisco. The vacationing families each take continuous trips to and from San Francisco. How many days will pass before the two vacationing families leave San Francisco on the same day again?
Answer by ikleyn(52756) (Show Source): You can put this solution on YOUR website!
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It is about finding the Least Common Multiple LCM  of the numbers  28 and 6.


    LCM(28,6) = 7*4*3 = 84.


ANSWER.  In 84 days.



To find LCM, you use prime decomposition of the two numbers, 28 and 6


    28 = 4*7 = ,   6 = 2*3.


Then you take all participating prime numbers, 2, 3 and 7,  and raise each prime to the maximum participating degree.


Doing this way, you get factors  , 3 and 7.


To get LCM, you multiply these factors.

Solved, explained, answered and completed.

Armed with this knowledge, you are in position now to solve thousands other similar problems (!)

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