5 1/6×6= 31/6*6=31

2 2/7*7= 16/7*7=16

11 1/8*4=89/8*4=89/2=44 1/2

6 1/9*18=55/9*18=110

(5/8+3/16)*16=(10/16+3/16)*16=13/16*16

=13

(8/21-3/14)*42=(16/42-9/42)*42=

7/42*42=7

1/6x+2/3x= 1/6х+4/6х=5/6х

4/17x-1/17x=3/17х

3 2/7y+1 1/14y= 3 4/14у+1 1/14у=4 5/14у

z-8/11z= 3/11z

2 3/5a+a= 3 3/5а

3/7x+11/7x=10

14/7х=10

2х=10

Х=10:2

Х=5

3/5y+13/20y-1/4y= 4

12/20у+13/20у-5/20у=4

У=4