tolong nya nomor 7,9,dan11 pakai cara please please

7.kpk=21=-x-x-x-x3x7
24=2x2x2x3
28=2x2x-x-x-x7
jadi kpk=2x2x2x3x7 ( B )
9.3=1x3
4=2x2
6=2x3
fpb=3 (C)
11.4 1/2+2 3/4+1/4+1 1/2=9/2+11/4+1/4+3/2=18/4+11/4+1/4+6/4=36/4=9kg (B)