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The amount at the account at the end of 5 years will be P*(1+0.04*5) = 1.2P,
where P is the principal.
The percentage of increase in 5 years is = 20%.
Tutor @Boreal mistakenly used the formula for a compound account, while the problem talks about a simple interest account.
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Comment from student : When I try to do it that way, I do not get 1.2p I get 1.000000102 Is p just 1? How did you get 1.2?
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My response : Try again.