7th Grade Math

216 Equations and Inequalities

Solve Multiplication Equations

Solve 20 = 4 x. Check your solution.

20 = 4 x Write the equation.

_^20

4

= _^4 x

4

Division Property of Equality

5 = x 20 ÷ 4 = 5

The solution is 5. Check the solution.

Solve - 8 y = 24. Check your solution.

• 8 y = 24 Write the equation.
  
  
  • 8 y
    _
  
  
  • 8
    = _^24
    
    
    • 8
      Division Property of Equality
      y = - 3 24 ÷ (-8) = - 3
      The solution is -3. Check the solution.
    
    
    
    
  
  
  
  

Solve each equation. Check your solution.

a. 30 = 6 x b. - 6 a = 36 c. - 9 d = - 72

TEXT MESSAGING Lelah sent 574 text messages last week. On

average, how many messages did she send each day?

Words

Variable

Equation

(^) Total is equal number of times number of
to days messages.
Let m represent the number of messages Lelah sent.
574 = 7 · m
574 = 7 m Write the equation.
^574
7
= ^7 m
7
Division Property of Equality
82 = m 574 ÷ 7 = 82
Lelah sent 82 messages on average each day.
d. TRAVEL Mrs. Acosta’s car can travel an average of 24 miles on
each gallon of gasoline. Write and solve an equation to find how
many gallons of gasoline she will need for a trip of 348 miles.
Real-World Link
Over 60% of
teenagers’ text
messages are sent
from their homes—
even when a landline
is available.
RR
O
214_226_C04L2_895130.indd 216 12/31/09 3:57 PM