Your question is –
Find the difference between ‘m and ‘n’, if it is given that, (m)2 – (n)2 =81 and the sum of these two variables is equal to 50.

It is a easy questions, If you see my explanation, I think, this questions answer will be clear to you.

Your Correct answer: c
Explanation:

According to the question,
(m)2 – (n)2 = 81….(i)
Sum of these two variables = sum of ‘m’ and ‘n’ = 50…..(ii)
We have to find the difference between ‘m’ and ‘n’ i.e. (m-n)
According to the standard mathematical formula,
(m)2 – (n)2 = (m + n) (m – n)
On substituting the values from equations (i) and (ii) in this formula we get,
81 = 50 (m – n)
∴ (m – n) = 81/50 = 1.62
Hence, the correct answer is option c.