If you draw only 25 balls, you could draw the 25 odd-numbered balls. However, there will then be no odd-numbered balls left, so when you draw two more you will be guaranteed to get two even-numbered balls. Thus, the minimum is 25+2=27 balls.
To find the slope ...
1) (5,-1)and(2,4)
4+1 / 2-5
5/-3
So slope for #1 would be -3/5
