Let A = the weight of arbequina olives in the mix
Let G = the weight of green olives in the mix
Since we know that the mix is 5 pounds total, we have this:
G + A = 5
G = 5 - A
We are asked for 5 pounds of mix that will sell for $6 per pound, so the total cost is $30.
Therefore, we can form the following equation:
A*9 + G*4 = 30
Using substitution, we can express G in terms of A:
9A + 4*(5-A) = 30
9A + 20 -4A = 30
5A + 20 = 30
5A = 10
A = 2
Therefore A = 2 and G = 3