The denominator will tell how many parts it takes to make a whole
Given that the two swimmers competed and Ursula's speed is 60 m/min while Andre's speed is 48 m/min. The distance that the Ursula will catch up with Andre will be:
distance=(relative speed)×(time)
relative speed=60-48=12 m/min
the two swimmers met at a distance of:
12×1
=12 meters
Let, the number = x
It would be: x + 15 = 2x - 56
2x - x = 15 + 56
x = 71
In short, Your Answer would be 71
Hope this helps!