We have to determine the factors which are not common in 15, 45 and 90.
Let us determine the factors of 15 first.
The factors are 1,3,5 and 15.
Let us determine the factors of 45.
The factors are 1,3,5,9,15 and 45.
Let us determine the factors of 90.
The factors are 1,2,3,5,6,9,10,15,18,30,45 and 90.
The factors which are not common factors of the given numbers are:
2,6,9,10,18,30,45,90.