The temperature was -2°F in the afternoon and is now -30°F. How many degrees did it drop?

28°

Step-by-step explanation:

Let's take 'x' as the number of how much degrees it dropped. So this is how the equation will look like:

-2 - x = -30

It is '-x' since the temperature 'decreased', so you must a subtract.

Take -30 to the other side and substitute it with '-x'. Since both the terms are shifted, -30 will be +30 and -x will be +x (which is equivalent to x).

x = -2 + 30

x = 28°

∴ There was a 28° drop.

for ex: the reciprocal of 3/4 is 4/3. it is the opposite.

reciprocal definition:

a mathematical expression or function so related to another that their product is one; the quantity obtained by dividing the number one by a given quantity.