Let's have B stand for burgers, and F stand for fries.
2.05B+0.85F=$19.10 - This equation is set equal to total price.
B+F=14 - This equation is set equal to total number of items.
Subtract the F in the bottom equation.
B=14-F
Put this in place of B in the first equation.
2.05(14-F)+0.85F=19.10
Make sure you distribute the 2.05 properly, over both the 14 and the F.
28.7 - 2.05F+0.85F=19.10
Collect like terms for the F values.
28.7 - 1.2F=19.10
Subtract 28.7 from both sides.
-1.2F=-9.6
Divide by -1.2 on both sides.
F=8
Put this value in place of F in either equation.
B+8=14
B=6
So F=8 and B=6.
