You have to get y on one side and numbers on another. So the best way to do this would be to move the 6y over to the left. To do that you have to subtract 6y from both sides.
7y-8=6y+1
-6y -6y
We subtract because we need it to zero out on the right.
7y-6y-8=1
Now move the -8 to the right by adding it to both sides.
7y-6y-8=1
+8 +8
7y-6y=1+8
remember we added 8 so that this number zeroed out on the left.
Now finish the math
7y-6y=1y or just y
1+8 =9
y=9