
is to say

for all

beyond some fixed

.
Similarly,

is to say

for all

.
From this we can gather that

where

is the larger of the two values

and

, or

. Then the last term is bounded above by

from which it follows that
3% interest on 5,000 = 150
275 (the total amount wanted) - 150 (from initial investment)= 125
x (5%) =125
x (0.05)= 125
x/0.05)= 125/0.05
x=2500
you need to invest 2500 at 5% to get the additional 125
125 plus 150= 275