Question 547100: aling martha invested part of her P20,000 at 8% interest and the remaining at 7%. If the total earnings for the investment is P1520, how much did she invest at 8%?
Answer by mananth(16949)   (Show Source):
You can put this solution on YOUR website! Fund A 8.00% per annum ---x
Fund B 7.00% per annum ---y
x + y= 20000 ------------------------1
8.00% x + 7.00% y= = $1,520.00
Multiply by 100
8 x + 7 y= = $152,000.00 --------2
Multiply (1) by -8
we get
-8 x -8 y= = -160000.00
Add this to (2)
0 x -1 y= = -P8,000.00
divide by -1
y = P8,000.00 investment at 7.00%
Balance P12,000.00 investment at 8.00%
CHECK
$12,000.00 --------- 8.00% ------- P960.00
$8,000.00 ------- 7.00% ------- P560.00
Total -------------- P1,520.00
| |
|
