Algebra 1
posted by Mbaintu on .
You have $6000 to invest in two stock funds. The first fund pays 5% annual interest and the second account pays 9% annual interest. If after a year you have made $380 in interest, how much money did you invest in each account?

I = P*r1*t+P*r2*t = $380.
I = P1*.05*1+P2*.09*1 = 380
0.05P1 + 0.09P2 = 380.
Multiply both sides by 100:
Eq1: 5P1 + 9P2 = 38000.
Eq2: P1 + P2 = 6000.
Multiply Eq2 by 5:
5P1 + 9P2 = 38000
5P1 + 5P2 = 30000
Add the 2 Eqs and 
I = P*r1*t+P*r2*t = $380.
I = P1*.05*1+P2*.09*1 = 380
0.05P1 + 0.09P2 = 380.
Multiply both sides by 100:
Eq1: 5P1 + 9P2 = 38000.
Eq2: P1 + P2 = 6000.
Multiply Eq2 by 5:
5P1 + 9P2 = 38000
5P1 + 5P2 = 30000
Add the 2 Eqs:
4P2 = 8000
P2 = $2000 = Investment @ 9%.
In Eq2, substitute 2000 for P2:
P1 + 2000 = 6000
P1 = $4000 = Investment @ 5%. 
thank you so much