Answer:
(5, 7, 15)
Step-by-step explanation:
A pair of numbers is coprime if the maximum number that divides the two is 1.
Consider the three numbers: 5, 7, 15
The first two numbers 5 and 7 can only be divided by 1. Hence the pair (5, 7) is coprime.
The second pair of numbers 7 and 15 is also coprime as the number which can divide both these numbers is 1. So the pair (7, 15) is also coprime
So, we have two pairs of coprime numbers: (5,7) and (7,15)
According to the friend, (5, 15) must also be coprime, but this not true as both these numbers can also be divided by 5.
Hence, the three numbers meeting the said criterion are: (5, 7, 15)
