Oh Foxy, Foxy, how totally debilitated you must be ! Try to relax. Nobody
enjoys a painful brain, and believe me, this problem is not worth it.
Let me put it to you this way: What if the problem said . . .
-- Demarcus has $8 more than his sister.
-- His sister has $4.
-- How much money ' M ' does Demarcus have ?
If your brain didn't hurt, you could quickly solve this right in there.
You would know that Demarcus' money ' M ' = 8 + 4 .
That's almost exactly what the problem does say.
Except it doesn't say he has "$8 more than his sister",
it says he has "at least" that much.
So you know that ' M ' is not exactly = 8 + 4, but that's the least it could be.
The actual amount of ' M ' is more than that.
Surely you can handle it from here, even with half of your brain
tied behind your back.
Take a good hard look at ' A ', and then go lie down.