The solution of the problem 1.17 cr 1 from the problem

The solution of the problem 1.17 cr 1 from the problem

Task 1.17
The radioactive core emitted from the accelerator at a rate of 0.8 s, ejected in the direction of its motion to the particle at a rate of 0.7 sec relative to the accelerator. Find the velocity of the particle relative to the nucleus.