Question 1186227
<br>
A standard formal algebraic solution....<br>
x = amount at 8%
120000-x = amount at 18%<br>
The total interest was 10000:<br>
.08(x)+.18(120000-x)=10000<br>
Solve using basic algebra; I leave that to you.<br>
If a formal algebraic solution is not required, here is a quick way to solve any 2-part mixture problem like this using a bit of mental arithmetic.<br>
(1) Calculate that 10000 interest on a loan of 120000 is a percentage rate of 8 1/3%.
(2) Picture the three percentage rates 8, 8 1/3, and 18 on a number line and observe/calculate that 8 1/3 is (1/3)/10 = 1/30 of the way from 8 to 18.
(3) That means 1/30 of the total was loaned at the higher rate.<br>
ANSWERS: 1/30 of 120000, or 4000 was loaned at 18%; the other 116000 at 8%<br>
CHECK: .08(116000)+.18(4000) = 9280+720=10000<br>