$300 at 4 percent for 3 years
A: Find the interest earned
B: Find the balance of the account

So this is a simple interest problem

Amount=principal(starting amount) * rate * time(In years)

So A= 300*0.04*3
A =36
So the interest earned was 36$ but since the balance started with 300$ you have to add 36$ to the old balance to find your new balance
Therefore your new balance would be 336$

Definitely