let a(x) be the amount of money remaining on hiliarys gift cards after purchasing x apps on her phone

Passengers usually start to board their flights 1 hour before the scheduled take off time. the gate will be closed 15 minutes before the takeoff time. jack’s plane is scheduled to take off at 12: 05 a. m. if he arrives at the gate at 11: 45 p. m., can he board the flight?

Can someone me with the property questions for 12 13 and 14 plz

Which expression demonstrates the use of the commutative property of addition in the first step of simplifying the expression (-1+i)+(21+5i)+0