Solve : $$\frac{{{{\left( {36.54} \right)}^2} - {{\left( {3.46} \right)}^2}}}{?} = 40$$

Let, the missing number be x,
Then,
$$\frac{{{{\left( {36.54} \right)}^2} - {{\left( {3.46} \right)}^2}}}{x} = 40$$
x = $$\frac{{{{\left( {36.54} \right)}^2} - {{\left( {3.46} \right)}^2}}}{40} $$
x = $$\frac{{{{\left( {36.54} \right)}^2} - {{\left( {3.46} \right)}^2}}}{{36.54 + 3.46}}$$
Let 36.54 = $$a$$ and 3.46 = $$b$$
x = $$\frac{{{a^2} - {b^2}}}{{a + b}}$$
x = (a - b)
x = (36.54 - 3.46)
x = 33.08