1) ( 4+9 ) . х =4х+9х
2) ( 17-3 ) . х = 17х-3х
3) ( х+6 ) . 5 =5х+6х
4) ( х-12 ) . 10 =10х-120
5) 6х + 3х = х(6+3)
6) 20х - 5х = х(20-5)
7) 6х + х = 7х
8) 10х -х = 9х
9) ( 2х + 7 ) . 5 = 10х+35
10) ( 5х - 1 ) . 12 = 60х-12
11) ( 1 + 3х ) . 30 = 30+90х
12) ( 40 - 8х ) .1 =40-8х