Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

Pages: **1**

**anonymous****Guest**

3/(5x+1)=2/9, x=?

**mathsyperson****Moderator**- Registered: 2005-06-22
- Posts: 4,900

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.

Offline

**ganesh****Administrator**- Registered: 2005-06-28
- Posts: 26,445

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

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

Offline

Pages: **1**