I need help with Use a system of linear equations with two variables and two equations to solve.

Question

If an investor invests $25,000  into two bonds, one that pays 4%  in simple interest, and the other paying 2%  simple interest, and the investor earns $700 annual interest, how much was invested in each account?

Answer 1

.04(x) + .02(25-x) = .7 where 25=$25,000, .7 = $700

.04x - 02x = .7-.02(25) = .7-.5 = .2

.02x = .2

x = .2/.02 = 20/2 = $10,000 invested at 4%

25-10 = $15,000 invested at 2%

.04(10,000) + .02(15,000) = 400 + 300 = $700