abby has 8 sports cards. she has either hockey or football cards she has 4 more hockey cards than football cards. how many football cards does she have?
H = F + 4
H + F = 8
Substitute F+4 for H.
F + 4 + F = 8
2F = 4
F = 2
H + F = 8
Substitute F+4 for H.
F + 4 + F = 8
2F = 4
F = 2