In the triangle below which is equivalent to sin a 30 60 90 triangle abc

12-3y=30x+6
-12 -12
-3y=30x-6
-3y/-3=30x/-3 -6/-3
y=-10x+2

So you basically want to isolate y so you would subtract 12 on both sides and you would be left with -3y=30x+6-12 then you would add like term which in this case would be 6 and -12 and you would get -6. After that just divide each number by -3, so it would be -3y divided by 3, 30x divided by -3 and -6 divided by -3.

Hope this helps!!