8 pounds. Because you'll need 4 pounds to make 10 apple pies, 6 pounds to make 15 apple pies, and 8 pounds to make 20 apple pies.
You can set this up as an algebraic equation using the ratio:

=

where x = number of skiers
Cross multiply:
x + 1250 = 2x
Solve for x:
-x = -1250
x=1250
To find the number of snowboarders, add 1250.
1250 + 1250 = 2500
1250 skiers and 2500 snowboarders bought season passes.
For A well I can't do a graph ,but to do it you would start at 50 going up 25 each week
For B it would be 300 because 25×10=250 plus the 50 from his grandmother he would have 300