Answer:
The answer has to 4 because 0+4=4
1)

3)

notice the rate "r"... now, is in decimal format, as you saw on 1) is just r/100 so 1.6% was really 1.6/100 or 0.016 anyhow
to get the percentage form, just multiply it by 100
The answer is 31.4. I hope this helps.