Answer:
$83,320
Explanation:
The formula to apply here is;

where;
A=Amount at the end
P=the amount to invest/principal
r=rate of interest as a decimal
n=number of compoundings in a year
t=time in years
Given that;
A=$400,000
P=?
r=8%=0.08
n=2
t=20
Substitute values in equation

P=$83,320 (to the nearest dollar)