Hai! So, I have all the math and explanations in the picture attached.
I forgot to add on there(and you'll see it) wen i subtract 3x and add 10 to the other side it cancels each other out. -3 + 3= 0 and -10 + 10 = 0. Etc.
Other than that, if you have any other questions, comment them down below. :)
