Page 69 - Math Skill - 5

Fractions 67

Let’s Attempt

Example 1: Add the following.
(a) 2 + 1 (b) 2 + 3 (c) 3 + 1
3 6 5 10 14 14

Solution: (a) 2 + 1 (b) 2 3
3 6 5 + 10
LCM of 3 and 6 = 6 LCM of 5 and 10 = 10

×
2 × 2 = 4 and 1 × 1 = 1 22× = 4 and 31 = 3
×
×
3 2 6 6 1 6 52 10 10 1 10
4 + 1 = 5 4 + 3 = 7
6 6 6 10 10 10
3 1 31+ 4 Fact-o-meter
(c) + = =
14 14 14 14 Always write the answer in the
smallest form and as a mixed
Example 2: Subtract the following. fraction (if improper fraction).

(a) 11 − 3 (b) 3 − 4 (c) 7 − 7
17 17 9 8 12

Solution: (a) 11 − 3 = 11 3− = 8
17 17 17 17

4 3 4 7 7
(b) 3 − = − (c) −
9 1 9 8 12
LCM of 1 and 9 is 9. LCM of 8 and 12 is 24.

39× = 27 and 41× = 4 73× = 21 and 72× = 14

19× 9 91× 9 83× 24 12 2× 24
27 − 4 = 27 4− = 23 = 2 5 21 − 14 = 7
9 9 9 9 9 24 24 24

2 3 1 Alternative Approach
Example 3: Add 1 , 2 and 3 · 2 3 1
5 10 5 1 + 2 + 3 = 6 +  2 + 3 + 1

5 10 5  5 10 5

2
+
×+
Solution: 1 = 15 2 = 52 = 7 LCM of 5, 10, 5 is 10.
5 5 5 5  43 2++ 
3 2103× + 20 3+ 23 = 6 +  
2 = = =  10 
10 10 10 10

1 35 1×+ 15 1+ 16 = 6 +  9  = 6 9

3 = = =  10 10

5 5 5 5