Answer
$\frac{a+2}{2(a+3)}$
Work Step by Step
Step 1: $\frac{3a}{2a+6}-\frac{a-1}{a+3}$
Step 2: $\frac{3a\times1}{(2a+6)\times1}-\frac{(a-1)\times2}{(a+3)\times2}$
Step 3: $\frac{3a}{2a+6} -\frac{2(a-1)}{2(a+3)}$
Step 4: $\frac{3a}{2a+6} -\frac{(2a-2)}{2a+6}$
Step 5: $\frac{3a-(2a-2)}{2a+6}$
Step 6: $\frac{a+2}{2a+6}$
Step 7: $\frac{a+2}{2(a+3)}$
