=
edit: distributive property
If you like, you can think in terms of temperature.
If it was and the temperature dropped by then it will have fallen to
If it was and it fell by ,
it would be
means "subtract" 4
means "subtract" 4 and "subtract" 14.
That's subtract 18 altogether.
means "do the opposite" of subtract 18 from 9,
and since subtraction is the opposite of addition,
addition is the opposite of subtraction, then 9--18 is 9+18.
To get the hang of things, you can think that way.
-- is + because
If you take a positive # c
c
and you subtract a negitive number d
c-(-d)=r
You are taking away a bit less than nothing.
And if you are taking away less than nothing r must be moving further from nothing.
Like owning money.
I owe 5$ and someone subtracts 4 dollars from my debt, now I owe 1$
I.E.
-5--4=-1
idk if that helps just trying to put usefull info out there