After you deal with the $+9$, you should have an equation where $\frac{y}{5}$ equals some number. What is that number?

Once you have $\frac{y}{5} =$ (a number), what operation will undo dividing by 5 so that you can get $y$ by itself?

After you rearrange the equation to $y = (21 - 9) \times 5$ on paper, type (21 - 9) * 5 into Desmos. The output shown is the value of $y$ that solves the original equation.

Start with the equation:

To isolate the fraction with $y$, subtract 9 from both sides:

which simplifies to

Now you have

To undo the division by 5, multiply both sides of the equation by 5:

On the left side, the 5s cancel, leaving $y$ by itself:

Calculate $12 \times 5$:

so $y = 60$.

Quick check: substitute $y = 60$ into the original equation:

which matches the right side, so $y = 60$ is the correct solution.