Which pair of these numbers has 20 as a common factor?
2 and 3
2 and 6
20 and 40

20 and 40

Step-by-step explanation:

3x7 is 21 but thats only one too much it has to be 3 too much to go down one and be a factor

6x4 is 24 it has to be 6 too much to go down one to be a factor

20x1 and 40x1/2 are both factors unless your teacher doesn't include fractions, so just choose this for now and if you get it wrong ask your teacher because three and six arent