After playing 40 games, the Lesley basketball team had won 50% of the games. The additional games played gave the team a 20% total winning average. How many additional games must the team have won to obtain this average?  Choose the correct option:
A) 2
B) 15
C) 7
D) 10
E) 9
Explanation: Identify the parts, set up equation, and solve.   Number of games initially won by the team:   50% * 40 = 20   Additional games won by the team leaving a 20% average. (Let x represent the unknown number of additional games won.) Therefore, the total number of games played is 40+x, and the total number of games won is 20+x. This gives the equation as:   20%*(40+x)=20+x   Solve: Let's get rid of the percent sign   20/100*(40+x)=20+x   1/5 *(40+x)=20+x   Get rid of the fraction:   5[1/5 * (40+x)]=5(20+x)   1 * (40+x) =100+5x   40+x =100+5x   (40-100)+x = (100-100)+5x   -60+x= 5x   -60+(x-x)+5x-x   -60=4x   15 = x   Answer: 15
<result>B</result>
After playing 40 games, the Lesley basketball team had won 50% of the games. The additional games played gave the team a 20% total winning average. How many additional games must the team have won to obtain this average?