Math Help - Simultaneous Equation

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Suppose the flight from Sydney to Perth takes t hours and the time difference between the two cities is d. The latter fact means that time(Sydney) = time(Perth) + d. Express the following through t and d and converting all time to 24-hour system.

(1) The time of Jim's arrival in Perth, Sydney time
(2) The time of Jim's arrival in Perth, Perth time
(3) The time of Jim's arrival in Sydney, Perth time
(4) The time of Jim's arrival in Sydney, Sydney time

Then the two equations are (2) = 12 and (4) = 5:35 pm (again, it should be converted to 24H).