Answer:
at 5% interest, she invested $8,000
at 6% interest, she invested $2,000
Explanation:
Let the invested amount at 5% interest = x
Let the invested amount at 6% interest = y
x = 4y - - - - (1) (A woman invested 4 times as much as 5% as she did at 6%)
5% of x = 0.05x
6% of y = 0.06y
0.05x + 0.06y = 520 - - - - (2) (The total amount of interest she earns is $520)
putting the value of x gotten in equation (1) into eqn (2):
0.05x + 0.06y = 520
where x = 4y
∴ 0.05(4y) + 0.06y = 520
0.2y + 0.06y = 520
0.26y = 520
y = 520 ÷ 0.26
y = $2000
from eqn (1)
x = 4y
since y = 2000
x = 4 × 2000
x = $8000