So here you're solving a system of equations. If A=the number of strokes Abby has, B=the number of strokes Brenda has, and C=the number of strokes Charda has, then your equations would be:
A-4=(A+B+C)/3 (A+B)+8=3C A+B+C=192
If we look carefully, you can see that (A+B+C) can be seen in two equations (the first and third). So you could use substitution with that.
A-4=(192/3) A-4=64 A=68
So now you know that Abby has 60 strokes, you can substitute that into any of the other equations. I chose the second and got:
68+B+8=3C B+76=3C B=3C-76
If you substitute this and Abby's score into the third equation, you get:
It has a fee of $15. If each copy is $.25 each and 200 copies are wanted, multiply them together to get 50. Add 50 and 15 to get 65. It cost $65 for 200 copies.