Question 345340
Let A be the amount invested at 7%, B the amount at 15%.
1.{{{A+B=8000}}}
2.{{{7A+15B=68000}}}
Multiply eq. 1 by (-7) and add to eq. 2,
{{{-7A-7B+7A+15B=-56000+68000}}}
{{{8B=12000}}}
{{{highlight(B=1500)}}}
Then from eq. 1,
{{{A+1500=8000}}}
{{{highlight(A=6500)}}}