4. Warren collects football cards and basketball cards. He
has a total of 140 cards. The number of football cards, f, is
two more than the number of basketball cards, b. Which
system of equations could be used to find out how many
football cards and how many basketball cards Warren has?
A f+ b = 140
f=b-2
B f-b=140
f-2=b
C f+ b = 140
f+b=2
D f+ b = 140
f=b+2