Question

A car travels a distance of 400 km and consumes x km per litre of fuel. Then the driver gets the engine serviced. The same car then travels a distance of 400 km but the fuel consumption is x+5 km per litre. How many litres of petrol was consumed by the car in total journey?

Answer 1

distance=400km
consumption=xkm per litre
fuel consumed=400/x
after servicing
 distance=400km
consumption rate=(x+5)
fuel consumed=400/(x+5)
total litres of fuel=400/x +400/(x+5)

Answer 2

Answer:

Step-by-step explanation:

Car A's consumption - Car B consumption = 4 liters

400%2Fx - 400%2F%28%28x%2B5%29%29 = 4

:

multiply by x(x+5) to clear the denominators, results:

400(x+5) - 400x = 4x(x+5)

400x + 2000 - 400x = 4x^2 + 20x

:

Combine like terms, A quadratic equation

4x^2 + 20x - 2000 = 0

;

simplify, divide by 4

x^2 + 5x - 500 = 0

:

Factors to

(x+25)(x-20) = 0

:

the positive solution

x = 20 km/liter for Car A

then

25 km/liter for Car B

therefore

Car B: 400%2F25 = 16 liters for 400 km journey

:

:

Confirm this solution by finding the consumption of Car A

400/20 = 20 liters, 4 liters more