*a number*means an arbitrary variable. We can pick any letter a-z except for i and e.

Let's choose x.

One-half a number means we divide x by2:

x/2

The word

*is*means equal to. We set x/2 equal to 50 for our algebraic expression

**x/2 = 50**

If the problem asks us to solve for x, we cross multiply:

x = 2 * 50

x =

**100**