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%