Alright, lets get started.
The amount of investment means principal : 42000
rate of interest : r : 4 % compounded annually
time of deposit t = 5 years
The formula for amount : A
A = P(1 + r/n)^nt
As interest is compounded annually, means n = 1
A = 42000 ( 1 + 4/100)^5
A = 42000 (1 + 0.04)^5
A = 42000 (1.04)^5
A = 42000 * 1.21665290
A = 51099.42 $
So the balance of Ila's account after 5 years will be 51099.42 $ : Answer
Hope it will help :)