A taxi driver filled his car petrol tank with 40 litres of petrol on Monday. The next day, he filled the tank with 50 litres of petrol. If the petrol costs Rs.44 per litre, how much did he spend in all on petrol?

Petrol filled on Monday = 40 liters.

Petrol filled the next day = 50 liters.

∴ Total petrol filled on the two days = 40 liters + 50 liters = 90 liters.

∴ Cost of petrol per liter = Rs. 44

∴ Cost of 90 liters petrol = Rs. 44 × 90 = Rs. 3960.