What will come in place of the question mark (?) in the following question?

$\frac{?+5}{7}+\frac{9}{21}=\frac{36}{21}$

The correct option is 4.

To find the value that replaces the question mark (?), let us represent it with the variable $x$. The given equation is:

$\frac{x+5}{7}+\frac{9}{21}=\frac{36}{21}$

First, isolate the term containing $x$ by subtracting $\frac{9}{21}$ from both sides of the equation:

$\frac{x+5}{7}=\frac{36}{21}-\frac{9}{21}$

Since the denominators on the right-hand side are the same, we can subtract the numerators directly:

$\frac{x+5}{7}=\frac{36-9}{21}$

$\frac{x+5}{7}=\frac{27}{21}$

Next, simplify the fraction $\frac{27}{21}$ by dividing both the numerator and the denominator by their greatest common divisor, which is 3:

$\frac{x+5}{7}=\frac{9}{7}$

Since the denominators on both sides are now 7, their numerators must be equal:

$x+5=9$

Subtract 5 from both sides to solve for $x$ :

$x=9-5$

$x=4$

Therefore, the number that comes in place of the question mark (?) is 4.