Page 71 - Maths Skills - 7

Rational Numbers 69

Exercise 4.3

1. Add the following rational numbers.

4 4 − 4 2 − 5 9 5 1
(i) and (ii) and (iii) 11 and −11 (iv) − 8 and 8
7 7 5 5
2. Add the following rational numbers.

19 7 33 17 − 7 5 − 9 22
(i) and (ii) and (iii) and (iv) and
8 3 18 26 27 18 10 15

3. Evaluate.
11 3 1 −12 5 − 4 − 3 8 − 2 13 11
(i) − 12 + − 8 + 4 (ii) + + (iii) + + (iv) + + 4
7 7 7 5 5 5 27 3
−15 − 8 − 8 − 7 5 − 4 7 4
(v) + (vi) 1+ + 5 (vii) 1+ + (viii) + +
27 3 13 12 6 3 18 21
4. Simplify.

− 9 5 − 7 14 1 7 11 − 8 2
(i) + (ii) + + (iii) −+1 + (iv) +
8 −16 20 −15 10 − 9 12 15 − 3

5. Add and write the sum as a mixed fraction.
− 23 1 18 − 6 −15 23 −101 11
(i) and (ii) − 11 and 5 (iii) and (iv) and −
8 4 7 −14 25 15
6. Find the additive inverse of each of the following.

21 2 −18
(i) – 17 (ii) (iii) (iv)
9 3 7
−16 15 − 2 −13
(v) − 5 (vi) − 7 (vii) (viii) − 38
9
3
6
7. Mohan travelled 3 km by walk and 2 km by train. Calculate the total distance he travelled?
7 8 1 1
8. Renu while making a summer drink mixes 3 L of rose flavour with 5 L of water. What will be the
5
4
quantity of drink made?
3 2
9. A submarine travelled 10 m below from the sea level and went 3 further down. Find the total
5 7
distance travelled by the submarine. What sign will you put in your final answer?

Subtraction of Rational Numbers
We know that subtraction is the inverse of addition, which means in subtraction we add the additive inverse of
one addend to the other addend.
p r r p
Thus, if and are any two rational numbers, then subtracting from means adding additive inverse of
q s s q

r
r to p , i.e., p −= p +  − r  .

s q q s q  s 
