The first question each friend gets 1/8 of the whole pizza
for half of the pizza each friend gets 1/4 so that times 2 equals 1/8
The second question one person gets 1/15 of the brownie pan
1/5 times 3 equals 1/15
The third question 1/3 cup one serving 1 cup three servings three times six equals 18 servings
The fourth question 1/5 cup one muffin one cup 5 muffins five times nine equals forty-five muffins
Hope this helps