Question 24500
Let x = the amount Sam invested at 5%, then ($15,000-x) = the amount invested at 3.5%. Change the percentages to their decimal equivalents and set up the equation to solve for x.
{{{(0.05)x + 0.035(15000-x) = 600}}} Simplify and solve for x.
{{{0.05x - 0.035x + 525 = 600}}} Combine like-terms.
{{{0.015x +525 = 600}}} Subtract 525 from both sides of the equation.
{{{0.015x = 75}}} Divide both sides by 0.015
{{{x = 5000}}}

Sam invested $5,000 at 5% interest and $15,000 - $5,000 = $10,000 at 3.5% interest.