40,000*(1.03)^x = 84,000*(0.98)^x
1.03^x=2.1*(0.98)^x
take log10 av both sides...x*log(1.03)=log(2.1)+x*log(0.98)
0.012837224705172283 x=0.32221929473392097 -0.008773924307505197x1929
0.0216114901267748x=0.32221929473392097
x=0.322219... / 0.02161149...
=14.909864104584212 yeers
or bout 15 yeers