I have a hard question to ask about math and planes?

Question

An aircraft flew 1,500 km to its target at the rate of 200 km per hour and returned to its base at the rate of 250 km per hour. It used 120 gallons of petrol per hour when flying at the rate of 200 km per hour and 150 gallons when flying at the rate of 250km per hour. How many gallons of petrol did the aircraft start its flight with if it still had 100 gallons of petrol when it returned?

Answer 1

amount of time going to the target: 1500 / 200 = 7.5 hrs

amount of petrol spent: 7.5 * 120 = 900 gallons

amount of time returning: 1500 / 250 = 6 hrs

amount of petrol spent: 6 * 150 = 900 gallons

thus total amount of petrol spent: 1800 gallons

original amount of petrol: (add 100.. . .) 1900 gallons

Answer 2

skip it  

Answer 3

x- [(1500/200)*120+

(1500/250)*150]

=100

x=100+7,5*120+6*150

x=100+900+900

x=1900 gallons

Answer 4

1500km/200km per hour=7.5 hours

     7.5 hours x 120 gallons per hour = 900 gallons

1500/250km per hour = 6 hours

     6 hours x 250 gallons per hour = 1500 gallons

900 on the way there+1500 on the way back+100 gallons to start= 2500                                                                            .                                                                                       total gallons