Answer:
4 questions
Explanation:
20= 100%
20 times 5 =100
100-80=20
peter got 20% of the test wrong.
i will say he missed 4 questions because you still have to multiply it by 5
4 times 5=20
or you could also do this
20-4= 16
16 times 5= 80
so, peter missed 4 questions