Abowling ball has a weight of 70 newton’s on earth. what is it’s mass on earth? what’s it mass on the moon?

Weight = (mass) x (gravity)

  70 N  =  (mass) x (9.8 m/s²)

Divide each side by  (9.8 m/s²) , and you have

    mass  =  70 N / 9.8 m/s²  =  7.14 kg.
 

Mass on the moon:

Mass doesn't change.  It's a number that belongs to the bowling ball,
no matter where the ball goes.  If the mass of the bowling ball is 7.14 kg
anywhere, then it's 7.14 kg everywhere ... on Earth, on the moon, on Mars, rolling around in the trunk of my car, or floating in intergalactic space.

However, WEIGHT depends on the gravity wherever the ball happens to be
at the moment.

The acceleration of gravity on the moon is 1.622 m/s².
So the WEIGHT of the ball on the moon is

        (7.14 kg) x (1.622 m/s²) =  11.58 Newtons

                             That's only about 16% of its weight on Earth.