Choice C is the correct answer. Let $x$ = amount at 4% and $y$ = amount at 6%.

Step 1: Set up the system: $\begin{cases} x + y = 5000 \\ 0.04x + 0.06y = 260 \end{cases}$

Step 2: From first equation: $x = 5000 - y$

Step 3: Substitute: $0.04(5000 - y) + 0.06y = 260$$200 - 0.04y + 0.06y = 260$$0.02y = 60$$y = 3000$

Solution: $3,000 was invested at 6%

Verification:

• $2,000 at 4%: $0.04(2000) = 80$
• $3,000 at 6%: $0.06(3000) = 180$
• Total interest: $80 + 180 = 260$ ✓

💡 Strategic Tip: Investment problems: (principal × rate) = interest earned.

Choice A is incorrect because $0.04(3000) + 0.06(2000) = 120 + 120 = 240 \ eq 260$.

Choice B is incorrect because $0.04(2500) + 0.06(2500) = 100 + 150 = 250 \ eq 260$.

Choice D is incorrect because $0.04(1500) + 0.06(3500) = 60 + 210 = 270 \ eq 260$.