Total number of games = 20
Number of games already played = 5
Number of games left = 15

Number of points after 5 games = 9
Number of points after 20 games = 40

So, they got to score 31 points in 15 games with the least number of wins

Here are a list of possibilities:

15 games, 10 wins and a draw = 10*3 + 1 = 31 Points
15 games, 9 wins and 4 draws = 9*3 + 4 = 31 points
15 games , 8 wins and 7 draws = 8*3 + 7 = 31 points
15 games, 7 wins and 10 draws = 7*3 + 10 = 31 points, but the total number of games is > 15 (17)

So the least number of wins to reach the 40 point mark = 8

Answer C

p.s: Sukh jee, can you please post the PS questions here -> https://www.beatthegmat.com/problem-solving-f6.html and DS questions here -> https://www.beatthegmat.com/data-sufficiency-f7.html

It is important to realize that the number of points from the draw also count.

So, easiest way is we know draw=1, win=3 and we have 15 games left

Set up equation

win(n games) + draw(15-n games) = 31 points

3(n) + 1(15-n)= 31
3n + 15- n = 31

2n = 16, n = 8

Answer: C, 8 wins