SOLUTION: Ladt year, Tammy had $30,000 to invest. She invested some of it in an account that paud 7% simple interest per year, and she invested the rest in an account that paid 8% simple int

Algebra.Com
Question 1101491: Ladt year, Tammy had $30,000 to invest. She invested some of it in an account that paud 7% simple interest per year, and she invested the rest in an account that paid 8% simple interest per year. After 1 year she recueved a total of $2280 in interest. How much did she invest in each account?
Thank you

Answer by richwmiller(17219)   (Show Source): You can put this solution on YOUR website!
Total amount of money invested: $30000
x+y=30000,
Total yearly interest for the two accounts is: $2280
0.07*x+0.08*y=2280
x=30000-y
Substitute for x
0.07*(30000-y)+0.08*y=2280
Multiply out
2100-0.07*y+0.08*y=2280
Combine like terms.
0.01*y=180
Isolate y
y=$18,000.00 at 8% earns $1,440 interest
x=30000-y
Calculate x
x=$12,000.00 at 7% earns $840 interest
Check
0.07*12000+0.08*18000=2280
840+1440=2280
2280=2280
If 2280=2280 is TRUE and neither x nor y is negative then all is well
codeint1

RELATED QUESTIONS

Last year, Ivanna had $10,000 to invest. She invested some of it in an account that paid... (answered by josgarithmetic)
Last year, Carlos had $30,000 to invest. He invested some of it in account that paid 10%... (answered by greenestamps)
Last year, Ann had $20,000 to invest. She invested some of it in an account that paid (answered by stanbon)
Last year, Latoya had $30,000 to invest. She invested some of it in an account that paid (answered by Boreal)
Last year, Dan had $10,000 to invest. He invested some of it in an account that paid 5%... (answered by josgarithmetic,greenestamps)
Last year, Teresa had to invest. She invested some of it in an account that paid simple... (answered by stanbon)
Last year, Michael had $20,000 to invest. He invested some of it in an account that paid... (answered by ikleyn)
Last year, Kareem had $10,000 to invest. He invested some of it in an account that paid... (answered by ikleyn)
Last year, Lucy had $10,000 to invest. He invested some of it in an account that paid 9%... (answered by ikleyn)