SOLUTION: I need help in this problem, thank you so much. How can $42,000 be invested, part at 4% annual simple interest and the remainder at 10% annual simple interest, so that the inte

Algebra ->  Equations -> SOLUTION: I need help in this problem, thank you so much. How can $42,000 be invested, part at 4% annual simple interest and the remainder at 10% annual simple interest, so that the inte      Log On


   

Question 682829: I need help in this problem, thank you so much.
How can $42,000 be invested, part at 4% annual simple interest and the remainder at 10% annual simple interest, so that the interest earned by the two accounts is equal at the end of the year?
Answer by ReadingBoosters(3246) About Me  (Show Source):
You can put this solution on YOUR website!
total = x+y = 42000 ($ in x or 4% and $ in y or 10%)
.04x = .10y (interest from x, which is .04 times $ invested should be the same or = interest from
y, which is .10 times $ invested)
.04(42000-y) = .10y ⇒ substituting x = 42000-y
1680 - .04y = .10y
1680 = .10y + .04y
1680 = .14y
y = 12000 at 10% (CHECK: .10(12000) = 1200)
x = 42000 - 12000 = 30000 at 4% (CHECK: .04(30000) = 1200)