Answer:
The next day they will be altogether in the gym is the 180th day after their last meeting
Explanation:
Given
Nick = once in 12 days.
Victoria = once in 20 days.
Boris = once in 18 days.
Required
The next day they will be there altogether
To get the next day they will be there altogether, we have to find the multiples of the given piece of data. The common factor is the answer (in other words, the next day they will be there altogether).
So;
For Nick (once in 12 days), this means we'll list out the multiples of 12.
Nick; 12,24,36,48,60,72,84,96,108,120,132,144,156,168,180,192,204.....
For Victoria (once in 20 days), this means we'll list out the multiples of 20.
Victoria; 20,40,60,80,100,120,140,160,180,200,220,240.....
For Boris (once in 18 days), this means we'll list out the multiples of 18.
Boris; 18,36,54,72,90,108,126,144,162,180,198,216......
The ........ signifies that the data continues but we had to stop
Having listed out the multiples of the given data, the next step is to identify the common factor.
The common factor is 180.
Hence, the next day they will be altogether in the gym is the 180th day after their last meeting