Free help with homework

Why join Brainly?

  • ask questions about your assignment
  • get answers with explanations
  • find similar questions



This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
This type of problem is a Work Problem.
We can solve this problem by using the formula
1/x + 1/y = 1/z,
where; x = time taken by Sonny
            y = time taken by his brother
            z = time taken by Sonny and his brother

The given in the problem is the time taken by Sonny which is 15 days and the time taken by both of them is 4 days
Since Sonny worked for 6 days already instead of 15 days, he has supposed to have remaining of 9 days to do the job alone but his brother helped him so they do the job together for 4 days only instead of 9 days.

We will now look for the time his brother do the job alone
1/x + 1/y = 1/z
1/9 + 1/y = 1/4
1/y = 1/4 - 1/9
1/y = (9-4)/36
1/y = 5/36
5y = 36
y = 36/5
y = 7.2

Therefore, Sonny's brother will take 7.2 days to do the job alone

0 0 0
The Brain
  • The Brain
  • Helper
Not sure about the answer?
Learn more with Brainly!
Having trouble with your homework?
Get free help!
  • 80% of questions are answered in under 10 minutes
  • Answers come with explanations, so that you can learn
  • Answer quality is ensured by our experts