The perimeter of the room is given by the formula
[tex]P=2L+2W[/tex]we have
L=10 ft
W=8 ft
substitute
[tex]\begin{gathered} P=2(10)+2(8) \\ P=36\text{ ft} \end{gathered}[/tex]Multiply the perimeter by the trim cost ($2 per foot)
[tex]\begin{gathered} total\text{ cost=36\lparen2\rparen} \\ total\text{ cost=}\$72 \end{gathered}[/tex]