Simple interest is
So say and . This describes the two investment conditions you listed.
Also we know that and
Can you take it from here?
Hello, trapt2006@sbcglobal.net!
Try some baby-talk . . .
Victor has invested $4000 into two accounts, part at 5% and part at 9%.
Find how much he invested at each rate if the total interest after 1 year is $311.
He invested dollars at 5%.
. . This will earn: dollars in interest in one year.
He invested the rest at 9%.
. . This will earn: dollars in interest in one year.
His total interest is $311: .
and there is our equation!