Title: Lesson 1-7
Author: mark_cameron
Last saved by: MHE
Company: McGraw-Hill

Lesson 2-1

For Example 1  Solve Equations by Substitution
a. Which of the numbers 7, 8, or 9 is the solution for d + 4 = 12?

Value of d | d + 4  12 | Are Both Sides Equal?

7

7 + 4 = 12
      11 ≠ 12

no

8

8 + 4 = 12
      12 = 12

yes  ✓

9

9 + 4 = 12
      13 ≠ 12

no

The solution is 8.

For Examples 2-4  Solve Equations Using Mental Math
b. Solve p – 4 = 9 using mental math.

  p – 4 = 9	What number minus 4 equals 9?
13 – 4 = 9	13 – 4 = 9
      9 = 9	

So, p = 13.

For Examples 5-6  Write and Solve Equations
c. [Real World Example] NUMBER SENSE   A number is 10 more than another number.  If the lesser number is 27, what is the greater number?

Let g represent the greater number.		Define the variable.

[align equal signs]

	g – 10 	=  27				Write an equation for the lesser number.

g – 10 + 10 	=  27 + 10			What number minus 10 equals 27?
	g	=  37