A grain dealer mixed wheat costing $0.90 a bushel with wheat costing $0.65 a bushel and sold the mixture at $1.00 a bushel. He made a profit of %25 of the total cost. In what proportions did he mix the wheat?

Assuming the percentage of the wheat of $0.90 a bushel in the mixture is x, then the percentage of the wheat of $0.65 a bushel in the mixture would be (1-x)

The cost of the mixture=0.90x+(1-x)0.65=0.90x+0.65-0.65x=0.25x+0.65

Since the price of the mixture is $1.00 a bushel and the profit is 25% of the total cost

(0.25x+0.65)(1+25%)=1

(0.25x+0.65)1.25=1

(0.25x+0.65)=1/1.25=0.8

0.25x=0.15

x=0.15/0.25=0.6=60%

So he mixed 60% the wheat costing $0.90 a bushel with 40% the wheat costing $0.65 a bushel.