Quantity I. A's salary is 40% of B's salary & B's salary 25% of C's salary. What percentage of C's salary is A's salary? Quantity Il. Two numbers are less than a third number by 30% and 37% respectively. How much percent is the second number less than the first?

To find the correct relationship between the two quantities, we will calculate the value of each quantity step-by-step.

Step 1: Calculate Quantity I
Let A's salary, B's salary, and C's salary be represented by $A$, $B$, and $C$ respectively.
According to the question, A's salary is 40% of B's salary:
$A=\frac{40}{100}\times B=0.4B$
And B's salary is 25% of C's salary:
$B=\frac{25}{100}\times C=0.25C$

Now, substitute the value of $B$ in the equation for $A$:
$A=0.4\times \left(0.25C\right)$
$A=0.1C$

To express A's salary as a percentage of C's salary:
$\text{Percentage}=\frac{A}{C}\times 100\%=\frac{0.1C}{C}\times 100\%=10\%$
Thus, Quantity I = 10%.

Step 2: Calculate Quantity II
Let the third number be 100.
The first number is 30% less than the third number:
$\text{First Number}=100-30=70$
The second number is 37% less than the third number:
$\text{Second Number}=100-37=63$

Now, we find how much percent the second number is less than the first number:
$\text{Difference}=70-63=7$
$\text{Percentage Less}=\frac{\text{Difference}}{\text{First Number}}\times 100\%$
$\text{Percentage Less}=\frac{7}{70}\times 100\%=10\%$
Thus, Quantity II = 10%.

Conclusion:
Comparing the two values:
Quantity I = 10%
Quantity II = 10%
Therefore, Quantity I = Quantity II.