Paul is running with a ke of 600 j if he starts at rest and his final velocity is 4 m/s what is his mass

We use the kinetic energy equation and substitute our data solving for the mass:
ke = (1/2)mv^2
m = 2*ke/v^2
m = 2*600/4^2
m = 1200/16
m = 75 kg
we can substitute directly because the units are homogeneus in the SI system: J, m/s, kg

Idon’t understand what you’re asking..

It says in the questions that it is 6.5?