Arabica coffee costs $28 per pound and Robusta coffee costs $8.75 per pound. How many pounds of Arabica coffee
must you mix with 3 pounds of Robusta coffee to make a
blend that costs $15.50 per pound?

Given parameters:

Cost per pound of Arabica coffee  = $28 per pound

Cost of Robusta coffee = $8.75

Given number of pounds of Robusta Coffee = 3 pounds

Total cost of blend per pound = $15.50

Unknown:

Number of pounds of Arabica coffee  = ?

Solution:

Let the number of pounds of Arabica coffee  = A;

  We have to interpret this problem algebraically and solve;

  28A + 8.75(3) = 15.5(A + 3)

Now solve the expression above for A;

       28A + 26.25 = 15.5A + 46.5

       28A - 15.5A  = 46.5 - 26.25

          12.5A = 20.25

                 A  = 1.62

Number of pounds of Arabica Coffee is 1.62 pound

since proposition states that a number is greater than 25, if is true then the number must actually be greater than 25.

this implies that all possible options, except 24, can be accepted