Linear equations with two variables word problem

Question

A baker purchased 12 lb of wheat flour and 15 lb of rye flour for a total cost of $39.87. A second purchase, at the same prices, included 15 lb of wheat flour and 10 lb of rye flour. The cost of the second purchase was $33.30. Find the cost per pound of the wheat and the flours.

Answer 1

Let x = the cost/pound of wheat flour

Let y = the cost/pound of rye flour

12x + 15y = 39.87     Multiply both sides of this equation by 2.

15x + 10y = 33.30     Multiply both sides of this equation by -3.

24x + 30y = 79.74

-45x -30y = -99.90

-21x = -20.16

x = $.96/pound

12(.96) + 15y = 39.87

11.52 + 15y = 39.87

15y = 28.35

y = $1.89/pound