The Winston Pool League played a total of 90 balls of which the ladies sank 30%. After getting a good night's sleep, the ladies came back the next day and sank each of the next balls played bringing their average to 50%. How many ball did the league play for the ladies to achieve this average?  Pick
A) 25
B) 30
C) 46
D) 26
E) 36
Explanation: Identify the parts, set up equation, and solve.   Number of balls initially sank by the ladies:   30% * 90 = 27   Total balls sank by the ladies leaving their average at 50%. (Let x represent the unknown number of additional balls sank by the ladies.) Therefore, the total number of balls played is 90+x, and the total number of balls sank by the ladies is 27+x. This gives the equation as:   50%*(90+x)=27+x   Solve: Let's get rid of the percent sign   50/100*(90+x)=27+x   1/2 *(90+x)=27+x   Get rid of the fraction:   2[1/2 * (90+x)]=2(27+x)   1 * (90+x) =54+2x   90+x =54+2x   (90-54)+x = (54-54)+2x   36+x= 2x   36=x   Answer: 36
<result>E</result>
The Winston Pool League played a total of 90 balls of which the ladies sank 30%. After getting a good night's sleep, the ladies came back the next day and sank each of the next balls played bringing their average to 50%. How many ball did the league play for the ladies to achieve this average?