Two numbers are 40% and 20% less than a third. what percentage of the first number forms of the second?

133·34%

Explanation:

Let the third number be x

40% of the third number is (40 ÷ 100) × x = 0·4 × x

As the first number is 40% less than the third number, it means that the first number is x - 0·4 × x = 0·6 × x

20% of the third number is (20 ÷ 100) × x = 0·2 × x

As the second number is 20% less than the third number, it means that the second number is x - 0·2 × x = 0·8 × x

Let the percentage of the first number that forms the second be k%

∴ (k ÷ 100) × 0·6 × x = 0·8 × x

⇒ (k ÷ 100) = 4 ÷ 3

∴ k ≈ 133·34

∴ The percentage of the first number that forms the second is 133·34%

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