Question

Erin invests $7000 in stocks and bonds. The bonds earn 5% annual interest and the stocks earn 8% interest. If she earns $404 in interest, how much does she invest in bonds?

Answer 1

`\large \boxed{\$5200}`

Explanation:

Let b = the amount invested in bonds

Then 7000 -b = the amount invested in stocks

0.05b = interest from bonds

0.08(7000 - b) = interest from stocks

`\begin{array}{rcll}0.05b +0.08(7000 - b) & = & 404 &\\0.05b + 560 - 0.08b&=&404&\text{Distributed the 0.08}\\-0.03b + 560 & = & 404 & \text{Simplified}\\-0.03b & = & -156 & \text{Subtracted 560 from each side}\\\\b & = & (-156)/(-0.03) & \text{Divided each side by -0.03}\\\\b & = &\mathbf{5200}\\\\\end{array}\\\text{Erin invests $\large \boxed{\mathbf{\$5200}}$ in bonds}`