There are:
Flavors = 20
Toppings = 8
We have to find the number of ice cream sundaes possible using 1 flavor and 1 toping. We have to use the multiplication rule of counting.
It tells us that if there are "x" ways of doing something and "y" ways of doing another thing, there there are a x b ways of doing the two actions.
Here, the number of sundaes will be the multiplication of both the number of flavors and number of toppings.
Hence,
You can make 160 different sundaes using 1 flavor and 1 toppings.