algebra
posted by RNRH .
Glenn invested some money is a certificate of deposit (CD) with an annual yield of 9%. He invested twice as much money in a mutual fund with an annualy yield of 12%. His interest from the two investments at the end of the year was $396. How much money was invested at each rate? (l=prt)

9% investment  $x
12% investment $ 2x
solve
.09x + .12(2x) = 396
I suggest multiplying each term by 100
9x + 12(2x) = 39600
etc