How can you translate a verbal sentence into an algebraic equation?

In one way, it's just common sense, but there are several phrases you need to be familiar with.

For example,

"5 less x" becomes 5-x.

"5 less than x" becomes x-5.

"5 is less than x" becomes 5<x.

"5 minus x" is 5-x, but

"5 subtracted from x" is x-5.

"5 diminished by x" is 5-x.

A good algebra book should have a list of 20 or so examples like this.