Question

What is the value of x?

Answer 1

Set up a proportion.

`(x)/(14 + x) = (9)/(9 + 12)`

Now cross multiply.

`x(9 + 12) = 9(14 + x)`

--->
`21x = 9x + 126`

Isolate variable x ---->
`21x - 9x = 126`

----->
`12x = 126`

Once again isolate variable x:

`(12x)/(12) = (126)/(12)`

x = 21/2 or 10.5.

Answer 2

These are similar triangles so

9/(9+12) = x/ (x+14)

using cross products

9*(x+14) = x*(9+12)

9x+126 = 21x

subtract 9x from each side

126 = 12x

x=10.5