let the amounts in the accounts be a and 9400 - a
using i = prt/100 where i is the interest earned
p is the principal, r is the rate and t is the time in year
Hence given that the total interest earned is 823
823 = (a * 7 * 1 + (9400 -a) * 10 *1)/100
82300 = 7a + 94000 -10a
10a - 7a = 94000 - 82300
3a = 11700
a = 11700/3
a = $3900
The amount invested in the second account is
9400 - 3900
= $5500
Hence there are $3900 and $5500 in the two accounts.