I hope this is the answer you want
Answer:
Fraction
Step-by-step explanation:
90% of the milkshakes had whipped cream because 90/100 as a percentage is 90%
When,
correct is 0 then p is 0/20.
correct is 1 p is 1/20
correct is 2 p is 2/20 that is 1/10
correct is 3 p is 3/20.
correct is 4 p is 4/20 that is 1/5
correct is 5 p is 5/20 that is 1/4