Question 366975
A store buys granola at $1/lb and dried fruit at $2/lb. and sells them at 25% markup. The store sells 2 special mixtures of granola and dried fruit.  One customer buys 6 lbs. of Mixture A and 4 lbs of Mixture B and pays $17.  Another custoemr reverses the proportions and pays a dollar more.   

Given:
Selling Prices
Granola     : $1 plus 25% mark-up = $1.25/lb
Dried Fruit : $2 plus 25% mark-up = $2.50/lb

Let A = Selling price of mixture A
    B = Selling price of mixture B

Equation 1
6A + 4B = 17

Equation 2
4A + 6B = 18
multiply equation 2 by 1.5 
6A + 9B = 27
deduct equation 2 by equation 1

(6A-6A)+ (9B-4B) = 27 -17
             5B  = 10
              B  = 2

substitute B=2 in equation1
6A + 4(2) = 17
      6A  = 17-8
       A  = 1.5

If mixtures A & B is sold at Granola = $1 plus 25% mark-up = $1.25/lb
& $2.00/lb respectively, we ca now compute the recipe for mixtures A & B

Given
Selling prices
Mixture A = $1.50/lb
Mixture B = $2.00/lb

Let x = % of Granola in mixture A
1.25x + 2.5(1-x) = 1.5
              x  = 80%
So recipe for mixture A is 80% Granola & 20% Dried Fruit

Let y = % 0f Granola in mixture B
1.25 y + 2.5(1-y) = 2
               y  = 40%
So recipe for mixture B is 40% Granola & 60% Dried Fruit