please answer this question

Dear student,

U \sin g m o m e n t u m c o n s e r v a t i o n, m_{1} u_{1} + m_{2} u_{2} = m_{1} v_{1} + m_{2} v_{2} ​ m_{1} = m a s s o f b o y m_{2} = m a s s o f b o a t m_{1} ​ = 40 k g, v_{1} = 2 m / s u_{1} = 0, u_{2} = 0 \Rightarrow 40 \times 0 + m_{2} \times 0 = 40 \times 2 + m_{2} v_{2} ​ \Rightarrow 0 + 0 = 80 + P b o a t 0 = 200 \times v + 80 v_{b o a t} = - \frac{80}{200} = 0.4 m / s

Regards