<span>w - amount of wheat purchased
r - amount of rye purchased
12w+15r=18.30 /*2
15w+10r=16.75 /*3
24w+30r=36.60, subtract this equation from the other one
45w+30r=50.25
21w=13.65
w=13.65/21
w=0.65 is a cost per pound for wheat flour
From the first equation we have
r=(18.30-12w)/15
r=(18.30-12*0.65)/15
r=0.70 is a cost per pound for rye flour</span>
