Two are solving equations, that's x, not multiplication sign)

1, 3/4 X minus 2/3X = 1/6

1/ 12x= 1/6

X =2

mistake

2,5/6 x minus 4/9= 16/9.

5/6x=20/9

x=20/9*6/5

X=8/3

correct

(The last two are calculations, and this is a multiplication sign. )

3、9/46× 1 1/ 12÷22/23

=9/46× 1 1/ 12×23/22

=3/ 16

correct

4、7/5×( 1/2-3/5÷ 18/5)

=7/5×( 1/2- 1/6)

=7/5× 1/3

=7/ 15

correct