$73 \times 18 + 486 = ? + (13)^{2}$

$A$ fraction is greater than its reciprocal by $\frac{9}{20}$. What is the fraction?

$\left[(72)^{2} \div 36+(?)^{2}\right] \div 5=45$

In a two-digit number, if it is known that its unit's digit exceeds its ten's digit by $2$, and that the product of the given number and the sum of its digits is equal to $144$, then the number is

$A$ fraction is greater than twice its reciprocal by $\frac{7}{15}$. What is the fraction?

How many natural numbers are there between $23$ and $100$ which are exactly divisible by $6$?