Assuming simple interest, let’s put x=the amount invested in the 3% account, then 7000-x will be invested in the 7% account.
The combined interest is 0.03x+0.07(7000-x)=262.
So 0.03x+490-0.07x=262, 490-262=0.04x, x=228/0.04=$5700 in the 3% account, so $1300 is invested in the 7% account.