Abaker purchased 12 pounds of wheat flour and 15 pounds of rye flour for a total cost of $18.30 a second purchase at the same prices including 15 pounds of wheat flour and 10 pounds of rye flour the cost of the second purchases was $16.75 for the cost per pound of the wheat flour and of the rye flour

cost of  wheat flour be = 0.682 $  per pound

cost of rye flour = 0.651 $  per pound

Step-by-step explanation:

Let the cost of  wheat flour be = x

cost of rye flour = y

so purchasing in first round to form a First equation  

12x + 15y = 18.30 equation 1

so purchasing in second round to form a Second equation:

15x +10y= 16.75equation 2

Solve equation 2 for y

15x +10y= 16.75

10y=16.75-15x

y=1.675-1.5x equation 3

Put the value of y in equation 1  

12x + 15y = 18.30

12x+15(1.675-1.5x)=18.3

12x-22.5x=18.3-25.125

-10.5x=-6.825

x=0.6825

Put the value of x in equation 3 to get y

y=1.675-1.5 (0.6825)  

y= 0.65125

cost of  wheat flour be = x = 0.682 $

cost of rye flour = y = 0.651 $

a_n = a_1 + (n - 1)d

the first term is 6.

the common difference d = ?

when you find d, replace n with 7 and d with the common difference to find your answer.