Each crate has 35 soccer balls, therefore if you had 4 crates that would be a total of 35 times 4, which equals 140 soccer balls. If you now changed the number of balls on the display, that means you are going to change the number of balls in each of the 4 crates. This means,rather than having 35 times 4, you will now have n times 4, where n is the number of balls in each crate (after you have changed the number of balls on display.
That would also mean the number of balls on 6 displays should have been, 35 times 6, which equals 210 soccer balls. But now the number of balls on 6 displays would be n times 6, where n is the new total number of balls (after the number on display have been changed from 35).