Answer:
25
Step-by-step explanation: (My way) If 20 questions equal 80%, then do 20/2 which equals 10. 10 is 40% because 20 was 80%, which was split in half. Now you do 10/2 which is 5. 10 was 40% so 40% got split into 20%. So then you have 5=20%, 10=40%. Now we multiply 10x2 which equals 20. 20=80% so now add 20+5 which is 25. 25 is 100%.
