30 because 0.3 * 100 = 30
C I’m pretty sure hope this helps
Use present value equation.
If present value of annuity equals 400,000, then you are indifferent.

where v = 1/(1+r) and A = annual payment = 800,000/20 = 40,000
PV = 400,000
After subbing in the numbers, the equation is:

Therefore at interest rate of about 7.75% you are indifferent.