40= 10 times 4 10 is breaken down to 2 times 5
bring down the 4 to get 2 times 5 times 4
Factor tree of 40: 40 20,2 10,2,2 5,2,2,2
40 20,2 10,2,2 5,2,2,2
40 20,2 10,2,2 5,2,2,2
40 20,2 10,2,2 5,2,2,2
40 20,2 10,2,2 5,2,2,2
40 20,2 10,2,2 5,2,2,2
It's 35
40 20,2 10,2,2 5,2,2,2
40 20,2 10,2,2 5,2,2,2
40 20,2 10,2,2 5,2,2,2
40/ \4*10/ \2*2 5*2Hope this helped you
All I did was make a factor tree. The GCF (Greatest Common Factor) is 5. :)