From conservation of momentum we have that:
[tex]0.35(20)-0.06(30)=0.35(10)+0.06v[/tex]Solving for v we have that:
[tex]\begin{gathered} 0.35(20)-0.06(30)=0.35(10)+0.06v \\ 7-1.8=3.5+0.06v \\ 0.06v=7-1.8-3.5 \\ 0.06v=1.7 \\ v=\frac{1.7}{0.06} \\ v=28.33 \end{gathered}[/tex]Therefore the velocity of the ball after the collision is 28.33 m/s