Question 166848
Principal times (% of Interest)=interest earned

we have to break the left hand side of this equation into two parts, one at 6% and one at 10%. We know the Total principal is  $9000 and we know the interest earned what we dont know is  how much of the 9000 was invested at each rate

so lets call the principal invested at 6%=x therefore the principal invested at

10% is 9000-x. Now we can write a formula with one unknown remembering that   6% is .06 in decimal form and  10% is .10 in decimal form.



6%(x)+10%(9000-x)=625.8---->.06x+.1(9000-x)=625.8--->.06x+900-.10x=625.8

900-625.8=.10x-.06x--->.04x=274.2  {{{x=6855}}}

so {{{highlight($6855)}}} was invested at 6%
and amount invested at 10%=9000-6855={{{highlight(2145)}}}