Yes, 1 and 11.
The simplified mixed number form of 25.15 is 253/20
-253
The number 5.
1
One.
Two.
29 is a prime number. Neither number goes into the other, and neither of them goes into the same number.
The largest prime under 20 is 19.
Only the number one.
The hcf of 15 and 20 is 5
55 goes into 20, 4 times.5 goes into 75, 15 times.
Their HCF is 4