Subtraction equations - Homework help

I need assistance in showing my son how to solve the following subtraction equations. I know that you are supposed to isolate the variable on one side. How would i do i solve the following problems. Thank you

18 - x = 4 (i know the answer is 14)
11= 15 - b ( i know the answer is 4)

when you are getting started write all of the steps out remember you want all the x's on one side and everything else on the other

18 - x = 4 so subtract 18 from both sides
18-18 - x = 4 -18
-x =-14 divide by -1
-x / -1 = - 14/-1
x= 14

11= 15 - b
11-15 = 15 - 15 -b
-4 = - b
b=4

okay for the first one do the opposite of x. so subtract 18 on both sides since you're trying to solve for x. then divide both sides by -1 since -x is multiplied by -1 in the first place. the main concept is to get x by itself. second one you have to subtract 15 on both sides and then divide by -1 on both sides. always remember that whatever variable you're trying to solve for do the opposite of whats being done with the variable.

If "you are supposed to isolate the variable on one side", try using inverse operations! For example, for 18-x=4, do the opposite of the math function, in this case subtraction, addition with the number on the left side and do this on the number on the right side.

x=4
x=|+18
x=|----------
x=|22

and.... x=22! This method is more on a 6-8th Grade level.

18 - x = 4
18 - x + x = 4 + x add x to each side
18 = 4 + x the x's on the left side cancel
18 - 4 = 4 + x - 4 subtract 4 from each side
14 = x do the arithmetic
x = 14 by symmetry

11 = 15 - b
b + 11 = 15 - b + b add b to each side
b + 11 = 15 the b's on the right side cancel
b + 11 - 11 = 15 - 11 subtract 11 from each side