Answer :
Multiples of a number are the numbers that a number can be divided by without any remainder.
The buses X and Y will leave at the same time by 8:40 am
To calculate when buses X and Y will leave at the time, we would have to find the Lowest Common Multiple of 20 and 25 minutes.
Find and list multiple until the first common multiple is found. This is the lowest common multiple.
Multiples of 20:
20, 40, 60, 80, 100, 120, 140
Multiples of 25:
25, 50, 75, 100, 125, 150
Therefore,
LCM(20, 25) = 100
The LCM is 100 minutes
Converting 100 minutes
60 minutes = 1 hour
100 minutes = ?
Cross Multiply
100 minutes x 1 hour / 60 minutes
= 1 2/3 hours.
This can be rewritten as :
= 1 hr 40 minutes
Adding this to 7am
7 am + 1 hr 40 minutes = 8 : 40am
Therefore, the buses X and Y will leave at the same time by 8:40 am
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