Can you tell me please

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?

What would be the reasons for lines 3 and 4? a. addition property; subtraction property b. addition property; solve c. substitution property; subtraction property d. substitution property; prove

Given the expression (7 ? 4i) ? (2 + 6i), perform the indicated operation and write the answer in the form a + bi.