A lorry was 3/5 full of petrol 21 litre was then added and it is now 5/6 full how many litre of petrol can the tank hold

Answer 1

Let x be the total capacity of the tank in liters.

Initially, the tank was 3/5 full, so the amount of petrol in the tank was (3/5)x liters.

21 liters was then added, so the new amount of petrol in the tank is (3/5)x + 21 liters.

Now, the tank is 5/6 full, so the amount of petrol in the tank is (5/6)x liters.

Since the amount of petrol in the tank before and after adding 21 liters is the same, we can write the equation as:

(3/5)x + 21 = (5/6)x

Multiplying by 30 to clear the denominators:

18x + 630 = 25x

Rearranging the terms:

7x = 630

Dividing by 7:

x = 90

Therefore, the tank can hold 90 liters of petrol.

Answer 2

or, with a lot less figuring,
5/6 - 3/5 = 7/30
so, if 7/30 of the tank is 21L, then the full tank holds
21 * 30/7 = 90L

Answer 3

Yes, that is correct. By finding the difference between 5/6 and 3/5, which is 7/30, we can directly determine that 7/30 of the tank capacity is equal to 21 liters. Therefore, the full tank capacity is found by multiplying 21 liters by 30/7 to get 90 liters. Thank you for the simplified explanation.