There is mistake in your question .
it should be x litres of fuel per kilometer
and then x+5 litres of fuel per kilometer.
Distance traveled before servicing the car = 400 km
fuel consumed per kilometer (in litres)= x
therefore total fuel consumed before servicing of car = 400*x
Distance traveled after servicing the car = 400 km
fuel consumed per kilometer (in litres)= x +5
therefore total fuel consumed after servicing of car = 400*(x+5)
hence total fuel consumed = 400x + 400x +2000
= 800x +2000
Since the data provided by the question is not sufficient to evaluate the value of x . Hence we get the answer in terms of x.
Hope This helps you!!
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