I need help with this

the pattern step number of second step is added to number of balls used of first step to get number of balls used of second step

that is

1 + 2 ( number of balls added to pattern step number) = 3 (number of balls used)

in the same way

6 + 4 = 10 ( first blank )

5 + 10= 15 ( second blank)

15 + 7 = 22 ( third blank )

22 + 8 = 30 ( fourth blank)