In a cricket match, 6 players had an average X of their runs. Average increases by 10 runs, if the seventh player makes a score of 112 runs. What is the average of the first 6 players?

The average of 6 players = X
Average increases by 10, when the seventh player makes a score of 112 runs.
Therefore, average of 7 players = X + 10
Average =Sum of Scores/Number of Players -------(1)
Here, average = X, number of players = 6
Hence,
Sum of scores = 6X
Score of 7 players = (Score of 6 players + score of 7 player) = (6X + 112)------- (2)
Total average = (X + 10) --------- (3)
Substitute (2) and (3), in (1)
(X + 10) = (6X + 112)/7
⇒ 7X + 70 = 6X + 112
⇒ 7X - 6X = 112 - 70
⇒ X = 42.