Answer:
10
Step-by-step explanation:
The greatest common factor (gcf) of two number(for integers), is the largest positive number that divides each one of them.
20 = 20 x 1 = 10 x 2 = 4 x 5
30 = 30 x 1 = 15 x 2 = 10 x 3 = 6 x 5
So listing every factor of each number we get
For 20, the factors are 1 - 2 - 4 - 5 - 10 -20
For 30, the factors are 1 - 3 - 5 - 6 - 10 - 15 - 30
As I highlighted up there, the common factor of 20 and 30 are 1 - 5 - 10.
Comparing them, we can see that 1 < 5 < 10
So, the greatest common facto of 20 and 30 is 10
