Confusion with Algebra (Substitution) I apologize for the title, I'm not sure what category this would fall under.
The advertisement read Buy $3$ tires at the regular price and get a fourth tire for only $3$ dollars. Carol paid $\$240$ for a set of $4$ tires. What is the regular price of a tire?
So I came up with $3x + 3 = 240$.
$\frac{240}{3} = 80$
$3 = 80$ does not make sense.
Why do I have to subtract the $3$ first? I was told that when using systems of equations I needed to use PEMDAS.

Your mistake is that dividing by three means you divide the entire left side, so you'd end up with: $$3x+3=240,$$$$\frac{3x+3}{3}=\frac{240}{3},$$$$x+1=80,$$$$x=\$79.$$ You omitted the $3x$ term in your calculations.
