Whether the ratios \frac{15}{36} and \frac{35}{42} are equivalent ratios.

Concept used:
Equivalent fractions are those fractions which have different numerators and denominators, but represent the same value or number. Equivalent fractions are reduced to the same fraction in their simplified forms.
Least Common Denominator (LCD) is the smallest number that is divisible by the denominator of all the fractions that are being added or subtracted.
If two fractions have the same denominator, then we can compare them by their numerators. The fraction with the greater numerator will be greater than the other fraction.
Calculation:
In order to check whether the fractions ${\displaystyle \frac{15}{36}}$ and ${\displaystyle \frac{35}{42}}$ are equivalent or no, first reduce both the fractions in the simplest form. And then check whether both fractions are equal or no.
Here observe that in the first fraction, ${\displaystyle \frac{15}{36}}$ the HCF of numerator and denominator is 3 and after that there is no other common factor than 1.
${\displaystyle \frac{15}{36}=\frac{5}{12}}$
Also observe that in the second fraction ${\displaystyle \frac{35}{42}}$ the HCF of numerator and denominator is 7. So the fraction can be simplified further dividing up and down by 7 and after 7 the fraction can be simplified further as shown below,
${\displaystyle \frac{35}{42}=\frac{5}{6}}$
So, in reduced form the ratios are ${\displaystyle \frac{5}{12}\text{and}\frac{5}{6}}$. The numerator of the first ratio is not equal to the numerator of the second, so they are not equal.
Thus, the given ratios are not equivalent.

Answer is given below (on video)