Question 399300
{{{a}}} = ounces of 30% solution to use
{{{(.3a + .35*12)/(a + 12) = .33}}}
{{{.3a + 4.2 = .33*(a + 12)}}}
{{{.3a + 4.2 = .33a + 3.96}}}
{{{.03a = 4.2 - 3.96}}}
{{{.03a = .24}}}
{{{a = 8}}}
8 ounces of the 30% solution are needed