SOLUTION: It takes 12 days for Wallace and Tina to finish the task. It takes 20 days for Wallace alone. How many days does Tina need to complete the task by herself?

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: It takes 12 days for Wallace and Tina to finish the task. It takes 20 days for Wallace alone. How many days does Tina need to complete the task by herself?      Log On


   

Question 755532: It takes 12 days for Wallace and Tina to finish the task. It takes 20 days for Wallace alone. How many days does Tina need to complete the task by herself?
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
1/x + 1/20 = 1/12

20/20x + x/20x = 1/12

(20 + x)/20x = 1/12

12(20 + x) = 20x*1

240 + 12x = 20x

240 = 20x - 12x

240 = 8x

240/8 = x

30 = x

x = 30

So Tina needs 30 days to do the job by herself.