let b = interest of bond, c = interest of money
a) D(money) = 50000 - 5000(b - c)
b) D(bond) = 50000 + 5000(b - c)
SUM = 50000 - 5000(b - c) + 50000 + 5000(b - c)
= 100000
c) conditions sets interest of money, "c" to 0.
thus c = 0
also, D(money) = 20000, and D(bond) = 80000...