Afootball player starts on the 20 yard line and gains 9 yards. on the next play, he loses 4 yards. the referee says there’s a penalty and takes away the 4-yard loss of yardage. which expression represents the total number of yards gained?
a) 20 + 9 – 4 – (−4)
b) 20 + 9 – 4 + (−4)
c) 20 + 9 – 4 – 4
d) 20 + 9 + 4 – (−4)