Total Quantity and Total Dollar Amount problem

Question

At an ice cream parior, ice cream cost $1.10 and sundaes $2.35. One day, the receipts for a total of 172 cones and sundaes were $294.20. How many cones were sold?

Answer 1

let x = # of cones

let y = # of sundaes

x + y = 172

solve for y

y = 172 - x

amount of sales =

1.10 x + 2.35 y = 294.20

substitute for y from first equation

1.10x + 2.35(172-x) = 294.20

1.10x + 404.20 - 2.35x = 294.20

-1.25x + 404.20 = 294.20

-1.25x = -110

x = 88

88 ice cream cones