Main Idea and New Vocabulary
NGSSS
Key Concept: Subtraction Property of Equality
Example 1: Solve Addition Equations
Example 2: Real-World Example
Key Concept: Addition Property of Equality
Example 3: Solve a Subtraction Equation
Example 4: Real-World Example: Solve a
Subtraction Equation
Five-Minute Check
• Solve addition and subtraction equations.
• equation
• equivalent equation
MA.7.A.3.3 Formulate and use different
strategies to solve one-step and two-step
linear equations, including equations with
rational coefficients.
Also addresses MA.7.A.3.2.
Solve Addition Equations
Solve 14 + y = 20. Check your solution.
14 + y =
– 14
20
= – 14
y =6
Write the equation.
Subtraction Property of Equality
Simplify.
Answer: The solution is 6.
Check
14 + y = 20
?
14 + 6 = 20
20 = 20 
Write the original equation.
Replace y with 6.
The sentence is true.
Solve 6 + x = 16. Check your solution.
A. 9
B. 10
C. 21
D. 22
FRUIT A grapefruit weighs 11 ounces, which is
6 ounces more than an apple. How much does
the apple weigh?
11 = a + 6
–6 =
5= a
–6
Write the equation.
Subtraction Property of Equality
Simplify.
Answer: The apple weighs 5 ounces.
SHOPPING A pair of sunglasses costs $25. A
book costs $10 less than the pair of sunglasses.
How much is the book?
A. $35
B. $34
C. $25
D. $15
Solve a Subtraction Equation
Solve 12 = z – 8. Check your solution.
12 = z – 8
+8 =
+8
20 = z
Write the equation.
Addition Property of Equality
Simplify.
Answer: The solution is 20.
Check
12 = z – 8
?
Write the original equation.
12 = 20 – 8
Replace z with 20.
12 = 12 
Simplify.
Solve 17 = y – 4. Check your solution.
A. 21
B. –21
C. 13
D. –13
Solve a Subtraction
Equation
MUSIC Vivian practiced the piano for 32 minutes.
She practiced 11 minutes less than her brother
did. How long did her brother practice the piano?
Solve a Subtraction
Equation
32 = b – 11
+ 11 =
43 = b
+ 11
Write the equation.
Addition Property of Equality
Simplify.
Answer: Vivian’s brother practiced piano for
43 minutes.
HEIGHT Seth is 68 inches tall, which is 4 inches
shorter than Abraham. How tall is Abraham?
A. 72 inches
B. 71 inches
C. 64 inches
D. 63 inches
Solve x + 31 = 53. Check your solution.
A. 84
B. 83
C. 22
D. 21
Solve –5 + y = 13. Check your solution.
A. 8
B. 9
C. 18
D. 19
Solve r – 7.2 = 22.8. Check your solution.
A. 14.6
B. 15.6
C. 29
D. 30
Solve –11 = 8 + a. Check your solution.
A. –3
B. 3
C. –19
D. 19
The sum of a number and 8 is –13. Find the
number.
A. –5
B. –6
C. –21
D. 21
Write and solve an equation to determine Dale’s
top speed at the racetrack if Dale’s top speed was
17 mph less than Andy’s.
A. s – 17 = 152; s = 169 mph
B. s – 17 = 152; s = 168 mph
C. 17 + s = 152; s = 135 mph
D. 17 + s = 152; s = 134 mph
The combined ages of the students in a 7th grade
class is 1,582. The combined ages of the students
in the 8th grade class is 34 more than the combined
ages of the students in the 7th grade class. Which
equation can help you find the combined ages of
the students in the 8th grade class?
A. h = 1,582 – 34
B. 1,582 – h = 34
C. 1,582 + 34 = h
D. 34 = h + 1,582