When the ratio are equated with each other known as proportion.
If the two ratios are given and the values in both the ratios are proportional to each other, then in this law, if the denominator of the first ratio is replaced with the numerator of the second ratio, the two ratio remains proportional to each other.
Alternendo law: If then .
For example: then using Alternendo law, the ratios will be then it implies that
Thus, if the denominator of the first ratio is replaced with the numerator of the second ratio, the two ratio remains proportional to each other.