Answer:
Step-by-step explanation:
Each of the 2-gallon mixes is made of 8 "parts" of paint, so each "part" is 2/8 gallons = 1/4 gallon = 1 quart. We can let b and y represent the costs of 1 quart of blue and yellow paint, respectively.
Then the cost for 2 gallons is ...
 3b + 5y = 58 . . . lime green
 6b +2y = 64 . . . ocean blue
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Subtracting the second equation from twice the first gives ...
 2(3b +5y) -(6b +2y) = 2(58) -(64)
 8y = 52
 y = 6.5
From the first equation, ...
 3b = 58 -5y = 58 -5·6.5 = 25.5
 b = 25.5/3 = 8.5
The cost of 1 quart of blue paint is $8.50; the cost of 1 quart of yellow paint is $6.50.