Chapter 3.5 (Mathematics 5)

Combined operations involving addition and subtraction

Combined operations involving addition and subtraction

Work out: 12 + 3 – 7

In pairs:

  1. Add 12 to 3.
    12  3 =  
  2. Subtract 7 from the sum in (1).
      7 = 

Discuss the results and share with other groups.

Example 5

Work out:

  1. 9 + 8 – 12
    Add 9 + 8 = 17
    Subtract 17 – 12 = 5​
    ​Thus 9 + 8 – 12 = 5
  2. ​25 + 82 – 64
    Add 25 + 82 = 107
    Subtract​ 107 – 64 = 43​

Exercise E

  • 6
  • 7
  • 12
  • 13

9 + 2 – 4 = 

8 + 5 – 7 = 

15 + 10 – 12 = 

18 + 15 – 20 = 

  1. 9 – 4 + 7 = 
  2. 15 – 10 + 18 = 
  3. 25 + 40 – 50 = 
  4. 63 + 87 – 72 = 
  5. 180 + 950 – 430 = 
  6. 430 + 680 – 590 = 

8  5  7 = 

E4

Chepkwony harvested 5 186 and 4 732 bags of maize from two different farms. He sold 8 209 bags of the maize. How many bags of maize remained?

E5

A trader had 25 760 bags of cement in the store. He sold 12 758 bags of the cement. At the same time he added 13 470 bags of cement in the store. How many bags of cement remained in the store?