Arithmetic Grade Six

Lesson One Hundred Sixty-four: Variables

There is an easy step-by-step way to solve variable problems. Here's one example: 


	5x - 2 = 13

	STEP ONE: ADD 2 to each side.
	  RESULT: 5x - 2 + 2 = 13 + 2
	  Since -2 + 2 = 0 and 13 + 2 = 15, we can rewrite like this:
		
		5x = 15

	  Now the solution is obvious:

		x = 3
Here's another example: 

	6y + 3 = 15

	STEP ONE: SUBTRACT 3 from each side.
	  RESULT: 6y + 3 - 3 = 15 - 3
	  Since 3 - 3 = 0 and 15 - 3 = 12, we can rewrite like this:
	
		6y = 12

	  Now the solution is obvious:

		y = 2
The strategy we use is to isolate the letter part on one side of the equal sign and the number part on the other. Here are three more examples: 

	6n - 2 = 34
	6n - 2 + 2 = 34 + 2
	6n = 36
	n = 6


	7a + 2 = 16
	7a + 2 - 2 = 16 - 2
	7a = 14
	a = 2


	8x + 3 = 27
	8x + 3 - 3 = 27 - 3
	8x = 24
	x = 3

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