Question 318823
Let A be the amount in 5% and B the amount in 6%.
1.{{{A+B=14000}}}
.
.
.
{{{0.05A+0.06B=780}}}
2.{{{5A+6B=78000}}}
Multiply eq. 1 by -5 and add it to eq. 2 to eliminate A.
{{{-5A-5B+5A+6B=-70000+78000}}}
{{{highlight(B=8000)}}}
Then from eq. 1,
{{{A+8000=14000}}}
{{{highlight(A=6000)}}}