Posted by Lauren on .
A proportion is shown below.
7/10 = 17.5/x
What is the value of x?

7th Grade Math 
Ms. Sue,
Ahh  ratios and proportions are soooo useful!
7/10 = 17.5/x
Cross multiply.
7x = 10 * 17.5
Solve for x.
7x = 175
x = 175/7
x = 25 
7th Grade Math 
Lauren,
this is how I solve, seems totally wrong.
(17.5*7)/10 = x
122.5/10 = x
12.25 = x
x = 12.25 
7th Grade Math 
Ms. Sue,
First, you could see it's wrong. Since 7 is less than 10, then 17.5 must be less than x.
Study this site, especially Method 1 under Solutions.
http://www.regentsprep.org/Regents/math/ALGEBRA/AO3/Lprop.htm 
7th Grade Math 
morgan,
thank you Ms.Sue :)

7th Grade Math 
Lauren,
Oh i see, thank you for the link, that helps a lot.

7th Grade Math 
Ms. Sue,
You're welcome.