A community for students.
Here's the question you clicked on:
 0 viewing
anonymous
 5 years ago
can anyone help me on this problem? "Mary's age is twice Fred's age and 1/3 of Sally's age. If the sum of their ages is 99 how old are they?
anonymous
 5 years ago
can anyone help me on this problem? "Mary's age is twice Fred's age and 1/3 of Sally's age. If the sum of their ages is 99 how old are they?

This Question is Closed

shadowfiend
 5 years ago
Best ResponseYou've already chosen the best response.0Let's call Mary's age \(m\), Fred's age \(f\), and Sally's age \(s\). Then: \[\begin{align} m &= 2f\\ m &= \frac{s}{3}\\ m + s + f &= 99 \end{align}\] We can solve this system of equations first by solving for \(s\) in terms of \(m\): \[s = 3m\] We already have \(m\) in terms of \(f\), which means we have \(s\) in terms of \(f\) as well: \(s = 3m = 3(2f) = 6f\). So we can plug into the last equation to solve for \(f\): \[\begin{align} 2f + 6f + f &= 99\\ 9f &= 99\\ f &= 11 \end{align}\] Is this enough for you to find the other ages?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0oh my goodness yes i think that helps SO much! THANK YOU!!!
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.