$6300 is invested, part of it at 10% and part of it at 9%. for a certain year, the total yield is $598.00. how much was invested at each rate?

Let x be sum invested at 9%
0.09x + 0.1 (6300-x) = 598
0.09x + 630 - 0.1x = 598
630-598 = 0.1x -0.09x
32 = 0.01x
x = 3200 - invested at 9%
and 6300-3200 = 3000 invested at 10%