Question

A plane flies 405 km on 90 litres of fuel how far can not go in 50 litres

Answer 1

Given that
For 90 lit of fuel plane flies = 405 km
For 1 lit of fuel plane flies = 405/90
                                           = 4.5 km

Therefore
For 50 lit of fuel plane flies = 50*4.5
                                              = 225 km.

The plane can fly 225 km using 50 liters o fuel.

Hope my answer helps you.

Answer 2

The answer is 225 KM, 

It flies for 405 KM in 90 liters of fuel, to get per liter mileage we need to divide 405 by 90 and the answer will be 4.5 KM per liter.

 Now we know it will travel 4.5 KM for 1 liter of fuel, to get the distance with 50 liter of fuel, you just need to multiply that by 50.   

50 X 4.5 and the answer will be 225 KM.

**Note - Answer is assuming that you typed "Not" by mistake in the question.