Question 404584
Let {{{a}}} = gallons of 3% solution needed
In words:
(gallons of salt in final solution)/(total final solution) = 4%
given:
{{{.03a}}} = gallons of salt in 3% solution
{{{.08*10 = .8}}} = gallons of salt in 8% solution
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{{{(.03a + .8)/(a + 10) = .04}}}
{{{.03a + .8 = .04*(a + 10)}}}
{{{.03a + .8 = .04a + .4}}}
{{{.01a = .4}}}
{{{a = 40}}} gallons
40 gallons of a 3% solution must be added
check answer:
{{{(.03a + .8)/(a + 10) = .04}}}
{{{(.03*40 + .8)/(40 + 10) = .04}}}
{{{(1.2 + .8)/50 = .04}}}
{{{2/50 = .04}}}
{{{2 = 50*.04}}}
{{{2 = 2}}}
OK