Explanation:
Pete has already completed 27 missions. Pete plans to complete 3 missions per week
Let x represents weeks
Games completed = 3x + 27
Sophie has only completed 13 missions. Sophie plans to complete 5 missions per week.
Games completed = 5x + 13
3x + 27 = 5x + 13
27 - 13 = 5x - 3x
2x = 14
x = 7
By the seventh week, they would have completed equal number of games,