Page 74 - Start Up Mathematics_5

2. Subtract the following fractions. Reduce the difference to the lowest term (if possible.)

42 68 74 97 7 13 8 11
(a) from (b) from (c) from (d) from
79 79 123 123 15 20 24 16

(e) 10 from 19 (f) 19 from 23 (g) 8 from 7 (h) 3 from 4
52 26 35 25 15 9 8 5
Addition and Subtraction of Whole Numbers and Fractions

Let’s learn to add and subtract a whole number and a fraction.
7
Example 16: Add 6 and .
9
Solution: We can write the whole number 6 as 6 .
1
7
Now we have to add 6 and . Remember
9
1
LCM of 1 and 9 is 9. Every whole number can
be written as a fraction
6 = 6 × 9 = 54 by writing 1 as the
1 1 × 9 9 denominator.

6 + 7 = 54 + 7 = 54 + 7 = 61 = 6 7
9 9 9 9 9 9
11
Example 17: Subtract from 4.
13
11 4 11
Solution: 4 – = –
13 1 13
LCM of 1 and 13 = 13
4 4 × 13 52
= =
1 1 × 13 13
11 52 11 52 – 11 41 2
4 – = – = = = 3
13 13 13 13 13 13

Addition and Subtraction of Mixed Fractions

We can add (or subtract) mixed fractions by either converting them to like fractions and
then adding (or subtracting) them or by adding (or subtracting) the whole numbers and
fractions separately.
3
2
Example 18: Add 4 and 3 .
5 7
3
Solution: 4 = (4 × 5) + 3 = 20 + 3 = 23
5 5 5 5
2
3 = (3 × 7) + 2 = 21 + 2 = 23
7 7 7 7
LCM of 5 and 7 = 35

23 = 23 × 7 = 161 23 = 23 × 5 = 115
5 5 × 7 35 7 7 × 5 35

2
3
4 + 3 = 161 + 115 = 276 = 7 31
5 7 35 35 35 35

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