Let's begin by listing out the information given to us:
Principal (p) = $20,000
Interest rate (r) = 5.2% = 0.052
Number of compounding (n) = 2 (semi annually)
Time (t) = 3 years
The total return is calculated as shown below:
A = p(1 + r/n)^nt
A = 20000(1 + 0.052/2)^2*3 = 20000(1 + 0.026)^6
A = 20000(1.1665) = 23,330
A = $23,330