Every number is the highest factor of itself.
obviously, its highest common factor is the number itself. so the answer here is 90.
90
That would be 15. Only a number ending in five would be a factor of 75. 45 is not. 35 is not. 25 is not. 15 is, and it also is a factor of 90. This makes it the highest common factor of 75 and 90, although it is not a prime factor.
The GCF of 60 and 90 is 30.
hcf(6, 90) = 6.
6
30
10
9
Ten and 90's highest common factor is ten.
25 and 90's highest common factor is five.
Five