To find the percentage variance in the net income you'll first subtract the original amount in income from the increase amount.
$52,360-$50,040 = $2,320
Then you'll want to divide the increase of $2,320 by the original net income of $50,040. $2,320/$50,040 = .0463
The final step is to multiply that number by 100.
.0463 x 100 = 4.63%