The amount needed in the account when Frost retires is given by the annuity formula. Compounding is 2 times per year.
.. A = Pi/(n(1 -(1 +r/n)^(-nt)))
.. 17900 = P*.08/(2*(1 -(1 +.08/2)^(-2*12)))
.. 17900 = P*.04/(1 -(1.04^-24))
.. P ≈ 272,920.64
The compound interest formula can be used to find the present value required. 4015 days is 11 years (ignoring leap years), so the amount to deposit can be calculated from
.. A = P*(1 +r/n)^(nt)
.. 272,920.64 = P*(1 +.08/2)^(2*11) = P*1.04^22
.. P ≈ 115,160.33
We don't know about the company's obligation to Robert. To fulfill its obligation to Frost, it must deposit 115,160.33 today.
Its upsidedown, witch one do you need help with?
Step-by-step explanation:

The multiplicative inverse of a number is the number when you multiply it, it gives you the product of 1.
So for - 27, what number will give us 1 when we multiply it by -27
-27 * -1/27 = 1
So the multiplicative inverse of -27 = -1/27
7/9 * 9/7 = 1
-9/16 * -16/9 = 1
So in essence, just take the number and flip it
-27 = -1 / 27
7/9 = 9/7
-9/16 = -16/9