If  12  : 1x   =  1x  : 18  , then what is the value of x?

4

Step by Step Explanation:
1. We have

 1 2
:
 1 x
=
 1 x
:
 1 8

⇒

 1 2

 1 x

=

 1 x

 1 8

Cross multiplying both the sides, we have

 1 x2
=
 1 16

⇒
 1 x
=
 1 4

⇒ x = 4

Thus, the value of x is 4.