Question 1163731
<br>
If a formal algebraic solution is not required, here is a quick and easy solution method.<br>
(1) All $21,000 at 6% would yield $1260 interest; all at 8% would yield $1680 interest.
(2) The actual interest, $1620, is 6/7 of the way from $1260 to $1680.  (Picture the three numbers on a number line -- 1260, 1620, and 1680.  1260 to 1680 is 420; 1260 to 1620 is 360; 360/420 = 6/7.)
(3) That means 6/7 of the total was invested at the higher rate.<br>
ANSWER: 6/7 of the $21,000, or $18,000, was invested at 8%; the other $3000 was invested at 6%.<br>
CHECK: .06(3000)+.08(18000) = 180+1440 = 1620<br>