Answer:
-20y
Explanation:
We can set up this equation as 5y*(-4y). Since the coefficients both have a variable of y, we can multiply these two terms together. We can multiply these as we normally would, and then at the end, add the variable. So, 5*(-4) is -20, and we can add our y on the end. Our final answer is -20y. Remember, if you multiply and there is one negative sign in the problem, the product will be negative. If there are two negative signs, the product is positive. In this case, there is one, so our product is negative. Hope this helps!