Answer:
You make one number positive.
Explanation:
A negative number multiplied by a negative number is positive, so that means that if you choose two of the numbers in this expression you will get a positive number. However, there is still one negative number left and you will get a negative product if you multiply, because a positive number multiplied by a negative number is a negative number. If you make this last number positive you will get a positive product.
Hope this helps!