Question

http://prntscr.com/94g298

Any help will be appreciated.

Answer 1

i think so answer is 7mn bcz
factors of 21 are 3,1,7,21
and factors of 28 are 1,2,4,7,28
gcf is 7
and now for 21m^2n/28mn^2
21m^2.n=3.7.m.m.n
and 28mn^2=7.4.m.n.n
so answer will be 7mn
B