What is the inverse of the following statement: if he speaks arabic, he can act as the interpreter.

Based on the given sentence above, the dependent clause is located at the first part of the sentence, then the independent clause follows next. Now, the correct inverse for it will be this:
He can act as the interpreter if he speaks Arabic. In this case, the independent clause is positioned in the first part of the sentence then the dependent clause followed. Hope this answer helps.