Let x represent invested money at 9% and y at 7%
Now we write system:
x+y = 6300
1.09x + 1.07 y = 6300 + 493 = 6793
1.09x + 1.09y = 6867
Here we multiplied first equation with 1.09 and now we will subtract second from first:
0.02y = 74
y = 3700
x = 6300-3700 = 2600
Michael invested 2600 at 9% and 3700 at 7%