Marcus is playing a video game. On his first win, he obtains 3 points. For every subsequent win, he will receive 2 additional points more than his previous win.

1. Identify the pattern of the scores

The score for the first win is $3$. For each subsequent win, the score increases by $2$. This forms a number sequence: $3, 5, 7, 9, \dots$

2. Calculate the score for the 6th win

The score for the $n$-th win is given by $3 + (n - 1) \times 2$.
For the 6th win ($n = 6$):
$\text{Score} = 3 + (6 - 1) \times 2 = 3 + 5 \times 2 = 13$

1. Formulate an expression for the score of the $n$-th win

The score for the $n$-th win forms a number pattern: $3, 5, 7, \dots$
The common difference is $2$.
Score for the $n$-th win $= 3 + (n - 1) \times 2 = 2n + 1$

2. Equate the expression to 99 and solve for $n$

$2n + 1 = 99$
$2n = 98$
$n = 49$