Does the volume change when the reactions occur?
A volume change from a reaction occurs if the difference in mole of gases does not equal to $0$

In order to find the answer for your question, we will have to add both reactions together, resulting in:
$$\ce{A + 4.5 B + C + 7.5 B -&gt; C + 2 D + 2 E + 8 D + 2E}$$
We can shorten the reaction by adding up all duplicates and removing both $\ce{C}$ from each side, resulting in:
$$\ce{A + 12 B -&gt; 10 D + 4E}$$
Now if we calculate the difference in mole gasses we get:
$$\Delta n = \pu{(10 + 4)mol} - \pu{(1 + 12)mol} = \pu{1 mol}$$
Based on the positiv difference in mole of gasses we can say that the reaction will change in volume, that is it will expand.