Answer :
[tex]\begin{gathered} Fa=2Fb \\ mx=\frac{my}{2} \\ Fa=mx(\alpha a),\text{ }Fb=my(\alpha b) \end{gathered}[/tex][tex]\begin{gathered} 2Fb=\frac{my}{2}(\alpha a) \\ Fb=my(\alpha b) \\ \\ \frac{my}{4}(\alpha a)=my(\alpha b) \\ \alpha a=4(\alpha b) \\ \end{gathered}[/tex]
Arrow X will have four times the acceleration of arrow Y.