GCF: Greater common factor
44+40=84
GCF of 44 is divided by 1,2,4,11,22,44
GCF of 40 is divided by 1,2,4,5,8,10,20,40
Circle the same number of both side you'll get 1,2,4 the greatest number is (4 ) they want the greatest number of both side you circle.
4/44=1
4/40=20
44+40=(4×1)+(4×20)=84
Hope this helps you.