If x : y = 7 : 3, then ($$x^2+y^2$$​ ) : ($$x^2-y^2$$) = ?

Correct option is A

Given:

x : y = 7 : 3

Concept Used:
For ratios, x : y = a : b .

$$\frac{x^2 + y^2}{x^2 - y^2} \\ \ \\ = \frac{(7k)^2 + (3k)^2}{(7k)^2 - (3k)^2} \\ \ \\= \frac{49k^2 + 9k^2}{49k^2 - 9k^2} \\ \ \\ = \frac{58k^2}{40k^2} \\ \ \\ = \frac{29}{20}$$​​