Your friend rent 10chairs and 2 tables for $300. another friend rent 8 chairs and 4 tables for $360 you want to rent 12 chairs and 3 tables how much do you expect to pay? ps i need it today

If x is chairs and y is tables then
10x+2y=300
8x+4y=360
solve for y and substitute to find x
10x+2y=300
2y=300 -10x
y=150 -5x so put 150 -5x in for y in the other equation
8x+4(150-5x)=360
8x+600-20x=360
-12x=-240
x= $20 per chair

put that in for x in either equation to find y
10(20)+2y=300
2y=300-200
y=100/2
y= $50 per table

12 chairs and 3 tables would cost 12(20)+3(50)=240+150=
$390

If you make it a little more clear i can answer it