Question 75961
I'm guessing as to where your fractions begin and end.  It helps us if you put the whole numerator in parentheses and the whole denominator in parentheses.
If I misinterpretted you, please let me know.
Add or subtract as indicated. Express your results in simplest form
5a – 12/ a^2 – 8a + 15 – 3a – 2/ a^2 – 8a + 15
{{{(5a-12)/(a^2-8a+15)-(3a-2)/(a^2-8a+15)}}}
{{{((5a-12)-(3a-2))/(a^2-8a+15)}}}
{{{(5a-12-3a+2)/(a^2-8a+15)}}}
{{{(2a-10)/(a^2-8a+15)}}}
{{{2(a-5)/((a-5)(a-3))}}}
{{{2*cross((a-5))/(cross((a-5))*(a-3))}}}
{{{highlight(2/(a-3))}}}
Happy Calculating!!!