The bag contains several balls of different masses. The mass of the lightest ball is 123 g

The bag contains several balls of different masses. The mass of the lightest ball is 123 g, and the heaviest one is 145 g, the total mass of all balls is 1015 g. How many balls are in the bag?

Maximum number of light balls in a bag:
(1015 – 145) / 123 = 7.07. Therefore, there will be no more than 7 light balls, since at least one ball must be heavier than 123 g.
Maximum number of heavy balls in a bag:
(1015 – 123) / 145 = 6.15. Consequently, the heavy balls will not be equal to 6, since then at least one ball will be heavier than 145 g.
From the previous conclusions it follows that there are 8 balls in a bag, 6 balls with the exception of the lightest and heaviest will have a mass range from 123 g to 145 g.