To determine the value of [tex]\( x \)[/tex] in the given proportion:
[tex]\[
\frac{10}{30} = \frac{x}{15}
\][/tex]
we can use the method of cross-multiplication. By cross-multiplying, we get an equation that eliminates the fractions:
[tex]\[
10 \times 15 = 30 \times x
\][/tex]
Now we simplify the multiplication on both sides:
[tex]\[
150 = 30x
\][/tex]
Next, we need to solve for [tex]\( x \)[/tex]. To isolate [tex]\( x \)[/tex], we divide both sides of the equation by 30:
[tex]\[
x = \frac{150}{30}
\][/tex]
Simplifying the division:
[tex]\[
x = 5
\][/tex]
Hence, the value of [tex]\( x \)[/tex] is [tex]\( 5 \)[/tex].
Therefore, the correct answer is:
C. 5
