Answer:
Option A.
Step-by-step explanation:
There are two fraction given in this question and we have to write the proportion using colon.
Visually fractions \(\frac{7}{21}\) and \(\frac{3}{9}\) are different but when we simplify these fractions we get the actual relation between them.
We simplify \(\frac{7}{21}\) first.
By dividing from 7 in the numerator and denominator we get
\(\frac{\frac{7}{7}}{\frac{21}{7}}=\frac{1}{3}\)
similarly we simplify the fraction \(\frac{3}{9}\)
By dividing numerator and denominator by 3
\(\frac{\frac{3}{3} }{\frac{9}{3} }=\frac{1}{3}\)
Now we can say that both the fractions are equal.
\(\frac{7}{21}=\frac{3}{9}=\frac{1}{3}\)
So the ratio will be 7 : 21 = 3 : 9
Option A. will be the answer.
