bob grey invests $22,000, some at 7% and some at 6% annual interest. if he receives an annual return of $1420, how much is invested at each rate?

Question

This is a question on a homework assignment that I can't figure out. I'm not sure how to set up the equation

Answer 1

1420/22000 = 6.454545..% average return on both investments

which is slightly closer to 6% than to 7%, so slightly more than $11,000 is invested at 6% than 7%

6%= .06, 7%= .07

.07x + .06(22000-x) = 1420

.07x -.06x = 1420 - .06(22,000)

.01x = 1420 -1320

x = 100/.01 = $10,000 invested at 7%

22000-x = $12,000 invested at 6%

.07(10,000) + .06(12,000) = 700+720 = 1420

Answer 2

0.06x + 0.07(22000 - x) = 1420

Can you solve for x and answer?