Answer:
$13,287.70
Step-by-step explanation:
The future value of the stock account is computed as the sum of a geometric series. This computation assumes that the annual yield is compounded monthly.
FV = p((1+r/12)^(12n) -1)/(r/12)
For the stock account, p=850, r=0.10, n=30, so the future values is ...
FV = 850((1+.10/12)^360-1)/(.10/12)) = 1,921,414.74
For the bond account, p=350, r=.06, n=30, so the future value is ...
FV = 350((1+.06/12)^360 -1)/(.06/12) = 351,580.26
The combined account value at the end of 30 years is ...
$1,921,414.74 + 351,580.26 = $2,272,995.00
_____
The monthly payment that can be made over a 25 year period is given by the amortization formula.
A = P(r/12)/(1 -(1 +r/12)^(-12n))
= $2,272,995.00(.05/12)/(1 -(1+.05/12)^-300) = $13,287.70
You can withdraw $13,287.70 each month assuming a 25-year withdrawal period.