In order to determine the converse of the given statement, first write the algebraic situation as follow:
If three less twice a number is equal to thirteen, then, such number is equal to minus five.
The converse of the previous statement is determine by identying the conditional and the conclusion of the statement. The conditional starts with "if ..." and the conclusion "then, ...". The converse is a statement with the previous conditional and conclusion inverted, just as follow:
If a number is minus five, then, three less twice such a number is equal to thirteen