.
We know two key circumstances: the ratio of the rates is  = 3  and the earned interests are the same.
It means that the 3% amount is three times as big as the 9% account.
So, let the accounts are x and 3x, respectively.
Then x + 3x = 10000  dollars,  hence,  x is $2500.
ANSWER.  $2500 invested at 9% and the rest,  $7500, is invested at 3%.
 = 3  and the earned interests are the same.
It means that the 3% amount is three times as big as the 9% account.
So, let the accounts are x and 3x, respectively.
Then x + 3x = 10000  dollars,  hence,  x is $2500.
ANSWER.  $2500 invested at 9% and the rest,  $7500, is invested at 3%.
Solved.