$6300 is invested,part of it at 10% and part of it at 7%.For a certain year, the total yield is $534.00. How much was invested at each rate

Answer 1

Invested:

$X @ 10%.
$Y @ 7%.

Eq1: x + y = 6300.
0.1x + 0.07y = 534.
Multiply both sides by 100:
Eq2: 10x + 7y = 53400.
Multiply Eq1 by -10.
-10x - 10y = -63000.
10x + 7y = 53400.
Sum: -3y = -9600.
Y = $3200.

x + y = 6300.
x + 3200 = 6300.
X = 6300 - 3200 = $3100.