#### Answer

$20$ is indeed a solution of this equation.

#### Work Step by Step

Let's plug in $20$ for $y$ to see if the equation holds true. If it does, then $20$ is a solution of the equation:
$$5(20) + 3 - 4(20) - 8 = 15$$
Let us do the multiplication first, according to order of operations:
$$100 + 3 - 80 - 8 = 15$$
Add and subtract, from left to right. We add $100$ and $3$:
$$103 - 80 - 8 = 15$$
Subtract $80$ from $103$:
$$23 - 8 = -15$$
Subtract $8$ from $23$:
$$15 = 15$$
Because the two sides of the equation equal one another, $20$ is indeed a solution of this equation.