Question

If y - 1 = 10 What is the variable of y?

Answer 1

Y-1=10
+1. +1

So y = 11
Hope that helps

Answer 2

y-1= -10
  +1  +1

y= -9

You have to add 1 in both sides, because of additive inverse.
-10+1 is -9.

Answer: y= -9
Check: y-1=10
-9-1= -10
-10= -10