So your object function is

and you want to maximize that subject to

.

Now,

and

.

Since you titled this "Lagrange multipliers", I assume you know that the optimum value will be where

for some number

. In this case, that means

so you have the two equations

and

. I recommend dividing one equation by another to eliminate

, that you don't really care about, and then using the constraint

to solve for

and

. Of course, you answers will be in terms of

,

,

,

, and I.

To answer the second question, subtract the result with "I" from the result with "

".