Question
Mr Heng's lorry was left with 13 fuel. He added 40 ℓ of fuel to his lorry, it became 79 full. How much more fuel was needed to fill up Mr Heng's lorry?
4 m

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Mr Heng's lorry was left with 13 fuel. He added 40 ℓ of fuel to his lorry, it became 79 full. How much more fuel was needed to fill up Mr Heng's lorry?