SOLUTION: Solve the problem. Roberto invested some money at 7%, and then invested $2,000 more than twice this amount at 11%. His total annual income from the two investments was $3,990. How

Algebra ->  Expressions-with-variables -> SOLUTION: Solve the problem. Roberto invested some money at 7%, and then invested $2,000 more than twice this amount at 11%. His total annual income from the two investments was $3,990. How       Log On


   

Question 170451: Solve the problem. Roberto invested some money at 7%, and then invested $2,000 more than twice this amount at 11%. His total annual income from the two investments was $3,990. How much was invested at 11%?
Answer by jojo14344(1513) About Me  (Show Source):
You can put this solution on YOUR website!
Let x ---> money inv. 7%
Therefore, 2x%2B2000 ---> money inv. @ 11%
It follows,
0.07x%2B%282x%2B2000%290.11=3990
0.07x%2B0.22x%2B220=3990
0.29x=3990-220=3770
cross%280.290%29x%2Fcross%280.29%29=cross%283770%2913000%2Fcross%280.29%29
x=$13,000, amount inv @ 7%
Then,
2%2A13000%2B2000=26000%2B2000=$28,000, amount inv at 11% (ANSWER)
Check,
0.07%2A13000%2B28000%280.11%29=3990
910%2B3080=3990
3990=3990
Thank you,
Jojo