Answer:
[tex]\large \boxed{\$5200}[/tex]
Step-by-step 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
[tex]\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 & = & \dfrac{-156}{-0.03} & \text{Divided each side by -0.03}\\\\b & = &\mathbf{5200}\\\\\end{array}\\\text{Erin invests $\large \boxed{\mathbf{\$5200}}$ in bonds}[/tex]
