28
Explanationto solve this we need to isolate y, to do that, we apply the addition property of equality, it states that If two expressions are equal to each other, and you add the same value to both sides of the equation, the equation will remain equal.
so
Step 1
given
[tex]y-7=21[/tex]add 7 in both sides
[tex]\begin{gathered} y-7=21 \\ y-7+7=21+7 \\ y=28 \end{gathered}[/tex]therefore, the answer is
28
I hope this helps you
