Answer:
To find the value of y, you need to isolate the variable. To do this, add 21 to -12. This gives you 9. Now, you're equation is set as 9 = y. This means that the value of y is 9.
Step-by-step explanation:
y=33
First you subtract 21 on both sides then you will get -y=-33 then you divide by -1 on both side and you will get y=33
