Question 1170291
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Short answer....<br>
51% is exactly halfway between 45% and 57%, so the two ingredients need to be mixed in equal amounts.<br>
ANSWER: 20 gallons.<br>
With formal algebra....<br>
45% of 20 gallons, plus 57% of x gallons, makes 51% of (20+x) gallons:<br>
{{{.45(20)+.57(x) = .51(20+x)}}}<br>
Solve using basic algebra....<br>