Two numbers are less than a third number by 64% and 25% respectively. The percentage of first number less than second number is:

Let's denote the third number as X.

1. The first number is less than X by 64%, so it is 36% of X. We can express this as 0.36X.

2. The second number is less than X by 25%, so it is 75% of X. We can express this as 0.75X.

3. We are asked to find the percentage of the first number less than the second number. This can be found by subtracting the first number from the second number, dividing by the second number, and then multiplying by 100 to get a percentage.

   So, the calculation would be: ((0.75X - 0.36X) / 0.75X) * 100

4. Simplifying the above expression gives: ((0.39X) / 0.75X) * 100

5. The X's cancel out, leaving: (0.39 / 0.75) * 100

6. Calculating the above expression gives approximately 52%.

So, the first number is approximately 52% less than the second number.