Answer :
We know each drink costs 3 dollars and each box of candy costs x dollars.
Charlie bought 2 drinks and 1 box of candy, so the expression is:
[tex]\text{Charlie spent=2}\cdot3+x=6+x[/tex]Tyrell bought 1 drink and 3 boxes of candy, so the expression is:
[tex]\text{Tyrell spent=1}\cdot3+3x=3+3x[/tex]The expression to know how muxh Charlie spent is:
[tex]\text{Charlie spent-Tyrell spent=(6+x)-(3+3x)=6-3+x-3x=3-2x}[/tex]So, the expression is 3-2x.