7+8+11=26
So the first manufacturer makes 7/26 of all filters
the socond one makes 8/26 of all filters
and the third one makes 11/26 of all filters
A)
Number of plastic filters A:

Number of plastic filters C:

B)
Number of plastic filters B:

85cents = 0,85$ (or €?)
Amount of money B will receive:

C)
The main thing that will change is the number of plastic filters to make:
1950-338=1612
So:
Number of plastic filters A:

Number of plastic filters B:

Number of plastic filters C: