To determine which of the given proportions is true, let's analyze each proportion step by step:
1. First Proportion:
[tex]\[
\frac{25}{40} = \frac{48}{80}
\][/tex]
To check this, we can cross-multiply:
[tex]\[
25 \times 80 = 2000 \text{ and } 40 \times 48 = 1920
\][/tex]
Since [tex]\(2000 \neq 1920\)[/tex], the first proportion is not true.
2. Second Proportion:
[tex]\[
\frac{18}{48} = \frac{27}{72}
\][/tex]
We cross-multiply:
[tex]\[
18 \times 72 = 1296 \text{ and } 48 \times 27 = 1296
\][/tex]
Since [tex]\(1296 = 1296\)[/tex], the second proportion is true.
3. Third Proportion:
[tex]\[
\frac{12}{15} = \frac{21}{25}
\][/tex]
We cross-multiply:
[tex]\[
12 \times 25 = 300 \text{ and } 15 \times 21 = 315
\][/tex]
Since [tex]\(300 \neq 315\)[/tex], the third proportion is not true.
4. Fourth Proportion:
[tex]\[
\frac{20}{48} = \frac{40}{98}
\][/tex]
We cross-multiply:
[tex]\[
20 \times 98 = 1960 \text{ and } 48 \times 40 = 1920
\][/tex]
Since [tex]\(1960 \neq 1920\)[/tex], the fourth proportion is not true.
After analyzing all the proportions, we find that only the second proportion is true:
[tex]\[
\frac{18}{48} = \frac{27}{72}
\][/tex]
So the correct answer is:
[tex]\[
\boxed{2}
\][/tex]
