Question

In his first three years of coaching basketball at North High School, Coach Lucas' team won 8 games the first year, 17 games the second year, and 6 games the third year. How many games does the team need to win in the fourth year so the coach's average will be 10 wins per year?

Answer 1

to have an average of 10 games in 4 years, they must have a total of 40 games

so far they have 8+17+6 = 31

so in the fourth year they need 9 games

or

(8+17+6+x)/4 = 10
31+x = 40
x = 9