Question

What is the value of x in the diagram? (diagram below)

Answer 1

The large triangle and the small triangle are similar (Can you guess why?)
This means that 9 / (9+4x-2) = 12 / (12+3x+2) = ...

Answer 2

4/21?

Answer 3

Let's see what steps we can take:\[\frac{ 9 }{ 7+4x }=\frac{ 12 }{ 14+3x } \Leftrightarrow \frac{ 3 }{ 7+4x }=\frac{ 4 }{ 14+3x }\]Now cross-multiply:\[3(14+3x)=4(7+4x) \Leftrightarrow 42+9x=28+16x\]Solution of this one is not 4/21....

Answer 4

44x

Answer 5

If I solve it, I do this:

42+9x=28+16x (subtract 9x from both sides):
42=28+7x (subtract 28):
14=2x (divide by 2):
x=2

Answer 6

Oops!
14=7x (divide by 7):
x=2

Answer 7

oh okay thanks!

Answer 8

YW!