Question

-y- 23= y- 16 you have to find y

Answer 1

-y-23 = y-16
-y+y-23=y+y-16 add y on both sides
-23+16=2y+16 add 16 on both sides
-7/2=2y/2 divide 2 on both sides
y=-7/2=-3.5 solution

Answer 2

Very easy. You isolate the y variable and solve from there:

-y-y = -16+23
-2y = 7
y = 7/-2