I think you need parentheses, but other than that, it looks about right. Try this version, with the parentheses included:

(10-3x)/( x^2-5x + 6 )

FYI, a quick way to add/subtract fractions - if you have to solve

A/B - C/D, you can solve it by simply calculating (AD-BC)/(BD). That's how I double-checked you. Similarly, A/B+C/D = (AD+BC)/(BD).

- Steve J