Question 948315
He invested x at 4% and x+3000 at 6%.
{{{0.04x+0.06(x+3000)=780}}}
{{{0.04x+0.06x+180=780}}}
{{{0.1x=600}}}
{{{x=6000}}} at 4%
So then,
{{{x+3000=9000}}} at 6%