if you have an problem like the on below and it says to subtract -23 from each sided to get the answer. so far so good

Because an equation represents a scale, it can also be manipulated like one. The diagram below shows a simple equation and the steps to solving it.

Initial Equation / Problem x + 23 = 45

Subtract 23 from each side x + 23 - 23 = 45 - 23

Result / Answer x = 2

(But then you get a problem like the one below)

The diagram below shows a more complex equation. This equation has both a constant and a variable on each side. Again, to solve this you must keep both sides of the equation equal; perform the same operation on each side to get the variable "x" alone. The steps to solving the equation are shown below.

Initial Equation / Problem: x + 23 = 2x + 45

Subtract x from each side x - x + 23 = 2x - x + 45

Result 23 = x + 45

Subtract 45 from each side 23 - 45 = x + 45 - 45

Result -22 = x

Answer x = -22

my question is how do you know what number or letter that has to be subtracked, that is where I am confused.

can somebody help