SOLUTION
Equivalent ratios are ratios that have the same proportion to each other when put in simplest form. They are sometimes refers to as equivalent fraction.
Given the ratio

To obtain the equivalence of the fraction above, we multiply the numertor and denominator by the same number.
hence

Then, multiplying both by 5, we have the equivalent fraction

convert the fraction to ratio, we have

Therefore
Answer: The equivalent ratio to 4 : 5 is 20 : 25