Set both equations equal to each first.
5x + 38 = 9x - 10
Then, you want to isolate x. Subtract 38 from both sides OR add 10 to both sides. You will notice that by performing the opposite of what the number value is by itself, will terminate the number on one side and add it to the other. (I will be subtracting 38 from both sides.)
5x = 9x - 48
Then, subtract 9x from both sides since it is positive and you need to do the opposite.
-4x = -48
Then, divide both sides by -4.
x = 12