The potential energy of an apple is 6.00 the apple is 3.00 meter high .what is the mass of the apple ?

Potential Energy = Mass x Gravitational Constant x height = mgh

6 = m(9.81)(3) 

Divide both sides by 9.81 and 3 to get m alone.

6 / (9.81 x 3) = 0.204 

Also, don't forget units! I'm not sure what your units are for the mass because you didn't give units for Potential Energy.

Well if you have 20 bats you probably want 20 balls? you don’t have enough context to answer the question.