Factors of 20:
1, 2, 4, 5, 10, 20
The common factors are: 1, 5.
The factors of 20 are 1, 2, 4, 5, 10, and 20. The factors of 30n would depend on the value of n. If n is a whole number, then the factors would include all the factors of 30 multiplied by n.
0.55
It is 9
75% of 20 is 15.
The LCM is: 220
2
13 and 7
17 out of 20 is 85%
15 is 75% of 20.
20 10,2 5,2,2
The HCF of 20 and 24 is 4.