To solve the problem, we first need to establish the relationship between the pairs of numbers in the given ratios.
The ratios provided, which are equivalent, can be written as fractions:
- \( \frac{3}{12} = \frac{1}{4} \)
- \( \frac{4}{16} = \frac{1}{4} \)
- \( \frac{5}{20} = \frac{1}{4} \)
From this, we see that each of these ratios simplifies to \( \frac{1}{4} \). This suggests that every pair of numbers in these ratios has a consistent proportion where the second number is always four times the first number.
Now, if the first number in the ratio is 10, we can use the same relationship to find the second number. According to the ratio we established (1:4), the second number can be calculated as:
\[ \text{Second number} = 10 \times 4 = 40 \]
Thus, if the first number is 10, the second number will be 40.
In summary, because the ratios all simplify to \( \frac{1}{4} \), the second number corresponding to a first number of 10 must be \( 40 \).