Your question is worded very well. But here is what I can make out of it.
I am assuming your interest is compound annually (once a year).
A = Final Amount $ P = Principal Amount $ R = Interest Rate % N = # of times interest is compounded per time period T = Time in Years I = Amount if Interest Earned $
A = ? P = ? R = 5% N = 1 T = 2 I = $1800
I solved for A and P. A = $19,360.98 P = $17,560.98
