#### Answer

$A(A(x))=1.04^{2}x$, amount of the investment after two years.
$A(A(A(x)))=1.04^{3}x$, amount of the investment after three years.
$A(A(A(A(x))))=1.04^{4}x$, amount of the investment after four years.
For $n$ copies of A, Amount=$1.04^nx$

#### Work Step by Step

$A(A(x))=A(1.04x)=1.04^{2}x$
This is the amount of the investment after two years.
$A(A(A(x)))=A(1.04^{2}x)=1.04^{3}x$
This is the amount of the investment after three years.
$A(A(A(A(x))))=A(1.04^{3}x)=1.04^{4}x$
This is the amount of the investment after four years.
For $n$ copies of A, Amount=$1.04^nx$