Let's assume the following :
x be the number of correct questions.
y be the number of incorrect questions.
z be the number of unattempted questions.
Given :
x + y + z = 75 …… (i)
3x - y + z = 97 …… (ii)
(2) - (1) ⇒ x - y = 11
(1) + (2) ⇒ 2x + z = 86
z > x + y
z > 75 - z
z > 37.5
From the above equation, we can assume that minimum possible value of z is 38.
2x + 38 = 86
2x = 48
x = 24
Therefore , the maximum number of correct questions solved is 24.