The denominator of the second fraction can be factored as (a-2)(2a-7), then it becomes doable. You cancel the (2a-7) factors, and are left with:
[tex]\frac{3a^2}{a(a-2)} \implies \frac{3a}{a-2} [/tex]
Do note that you have erased the fact that a≠0 and a≠7/2, so you should always mention that.
