Hiim can u plz answer this question showing all working out in as much detail as possible cuz i still dont understand the formula. Thanks!

Mrs Jones invests $4000 at 10% annual return and $6000 at 12% annual return. How much should she invest so that her total annaul return is 13% of the total amount she invested?

If u work this one out can u plz go to number 3 money/investment problem and try and help me with that! =)