Which expression represents the greatest common factor (gcf) of 30 and 80? a. 2 x 5 b. 2 x 7 c. 7 x 5 d. 2 x 2 x 5

30 = 5*6  = 5 * 3*2

80 = 8* 10 = 2*2*2 * 2 *5

The CGF is the numbers that appear in both  

2 appears 1 time in both and 5 appears 1 time in both

GCF 2*5

Choice A

the mistake in the pattern is that :

b. the decimal point was moved one too many place values each time

the correct pattern could be made by :

b. moving the decimal point to the right the same numbers of place values as the exponents