Negative numbers are more elusive than we think
What "intuition" are you looking for? And what is this "flipping" interpretation you seem to see?
You keep providing perfectly fine interpretations of performing operations with negatives, then immediately recoiling in fear. Why? Why do negatives give you the creeps?
Some folks like to think of math as the study of patterns. Consider the pattern of values on the right side of the equal signs, then complete the last equation :
-5 x 4 = -20
-5 x 3 = -15
-5 x 2 = -10
-5 x 1 = -5
-5 x 0 = 0
-5 x -1 = ___
(Hint : the values are increasing by a constant amount)
Oh, and my earlier comment can be improved upon - I was tired and writing in haste. Nothing wrong with the math, but here's a better explanation : Multiplying by signed numbers
is identical to repeated additions or subtractions,
but only if we start from 0. Your mistake was starting with a balance of $50. So subtracting $100 (2 x 50) seemed the same as multiplying the initial amount by -1 which made no sense.
If you can't handle negatives, you better avoid irrationals or complex numbers. You're clearly not ready for those. And don't even look up transcendentals. Ooh, the mind reels.