Answer :
About 25 gallons of 20% mixture are needed to make the 80% mixture.
What is an equation?
An equation is an expression that shows the relationship between two or more numbers and variables.
Let x represent the amount of gallons of 20% mixture needed, hence:
(20% of x) + (80% of y) = 65% of 100
0.2x + 0.8y = 65 (1)
Also:
x + y = 100 (2)
From both equations:
x = 25, y = 75
About 25 gallons of 20% mixture are needed to make the 80% mixture.
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