Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °
You are not logged in.
#2 2005-07-11 04:36:25
- mathsyperson
- Moderator
Offline
Re: proportions
3/(5x+1)=2/9
Multiply by (5x+1): 3=2(5x+1)/9
Multiply by 9: 27=2(5x+1)
Multiply out of brackets: 27=10x+2
Take away 2: 25=10x
Divide by 10: x=2.5
Hope this helps!
Why did the vector cross the road?
It wanted to be normal.
#3 2005-07-11 14:47:34
- ganesh
- Moderator
Online
Re: proportions
This can be explained in another way.
when you have a/b=c/d,
you get ad=bc.
In this problem,
3/(5x+1) = 2/9,
therefore, 9x3 = 2(5x+1)
27=10x+2
Move 2 to the other side, by changing the sign,
27-2 = 10x,
25=10x,
x = 25/10 = 2.5
Character is who you are when no one is looking.