7th Grade Math

and Apply

BAR DIAGRAM Draw a bar diagram and write an equation for each

situation. Then solve the equation.

3. The sum of a number and four is equal to 18.


4. Two more than the number of frogs is 4.


5. A number of students increased by 10 is 28.


6. A number decreased by 15 is 22.


7. BABYSITTING Katie earned $15 babysitting this week. Last week
   she earned $46. How much more did she earn last week than
   this week?


8. AGES The median age of people living in Arizona is 1 year older
   than the median age of people living in the United States. If the
   median age in Arizona is 34, what is the median age of people
   living in the United States?


9. E WRITE MATH Write a real-world problem that can be
   represented by the bar diagram below.

Lesson 1B Addition and Subtraction Equations 205

BASEBALL CARDS Jack had some baseball cards. He sold 7 of

them. Then he had 29 left. Write and solve a subtraction

equation to find the number he had at the beginning.

Draw a bar diagram representing the sentence.

Let n represent the number.

n baseball cards

7 29

sold number left

Write a subtraction equation from the bar diagram.

n^ -^7 =^29

Solve the equation by working backward. Since

n - 7 = 29, then n = 29 + 7. So, n = 36.

Check 36 - 7 = 29 

If 7 less than a number is 29, the number is 36.

n

$19 $8

money spent for DVD money left

204_213_C04L1_895130.indd 205 12/31/09 3:55 PM