[tex]x-\ cost\ of\ renting\ chair\\
y-\ cost\ of\ renting\ table\\\\
\left \{ {{10x+2y=300\ \ \ \ \ \ \ \ \ \ \ \ } \atop {8x+4y=360\ \ \ | divide\ by\ -2}} \right. \\\\
\left \{ {{10x+2y=300} \atop {-4x-2y=-180}} \right. \\\\+----\\addition\\\\\
6x=120\ \ \ | divide\ by\ 6\\\\
x=20\\\\
y=\frac{300-10x}{2}=150-5x=150-5*20=150-100=50\\\\
12x+3y=12*20+3*50=240+150=390\\\\
I\ am\ expected\ to\ pay\ 390\$[/tex]
