Answer :
The formula for compound interest is
[tex]A=P(1+r)^t[/tex]Where
A = final amount
P = principle amount
r = interest rate
t = period of time.
Now in our case,
A = 300
P = unknown
r = 4/100 0.04
t = 7 years
Putting the above values in the formula gives
[tex]300=P(1+0.04)^7[/tex]Solving for P gives
[tex]\frac{300}{\mleft(1+0.04\mright)^7}=P[/tex][tex]\therefore P=227.975[/tex]Hence, Erki has initially deposited $227.975.