Q.1: Find
(a) 35 – (20) (b) 72 – (90)
(c) (– 15) – (– 18) (d) (–20) – (13)
(e) 23 – (– 12) (f) (–32) – (– 40)
Ans:
(a) 35 – (20)
= 35 – 20
= 15
(b) 72 – (90)
= 72 – 90
= -18
(c) (-15) – (-18)
= -15 + 18
= 3
(d) (-20) – (13)
= -20 – 13
= -33
(e) 23 – (-12)
= 23 + 12
= 35
(f) (-32) – (-40)
= -32 + 40
= 8
Q.2: Fill in the blanks with >, < or = sign.
(a) (– 3) + (– 6) ______ (– 3) – (– 6)
(b) (– 21) – (– 10) _____ (– 31) + (– 11)
(c) 45 – (– 11) ______ 57 + (– 4)
(d) (– 25) – (– 42) _____ (– 42) – (– 25)
Ans:
(a) (– 3) + (– 6) ______ (– 3) – (– 6)
LHS = (-3) + (-6) = -9
RHS = (-3) – (-6) = -3 + 6 = 3
Since, -9 < 3
Therefore (-3) + (-6) < (-3) – (-6)
(b) (– 21) – (– 10) _____ (– 31) + (– 11)
LHS = -21 – (-10) = -21 + 10 = -11
RHS = -31 + (-11) =-31 -11 = – 42
Since, -11 > – 42
Therefore (-21) – (-10) > (-31) + (-11)
(d) (– 25) – (– 42) _____ (– 42) – (– 25)
LSH = (-25) – (- 42) = – 25 + 42 = 17
RHS = – 42 – (- 25) = – 42 + 25 = -17
Since, 17 > -17
Therefore (-25) – (-42) > (-42) – (-25)
(d) (– 25) – (– 42) _____ (– 42) – (– 25)
LSH = (-25) – (- 42) = – 25 + 42 = 17
RHS = – 42 – (- 25) = – 42 + 25 = -17
Since, 17 > -17
Therefore (-25) – (-42) > (-42) – (-25)
Q.3: Fill in the blanks.
(a) (– 8) + _____ = 0 (b) 13 + _____ = 0
(c) 12 + (– 12) = ____ (d) (– 4) + ____ = – 12
(e) ____ – 15 = – 10
Ans: (a) (-8) + 8 = 0
(b) 13 + (-13) = 0
(c) 12 + (-12) = 0
(d) (-4) + (-8) = -12
(e) 5 – 15 = -10
Q.4: Find
(a) (– 7) – 8 – (– 25)
(b) (– 13) + 32 – 8 – 1
(c) (– 7) + (– 8) + (– 90)
(d) 50 – (– 40) – (– 2)
Ans:
(a) (-7) – 8 – (-25)
= -7 – 8 + 25
= -15 + 25
= 10
(b) (-13) + 32 – 8 – 1
We can rearrange the numbers so that the positive integers and the negative integers are grouped together.
= -13 – 8 – 1 + 32
= -22 + 32
= 10
(c) (-7) + (-8) + (-90)
= -7 – 8 – 90
= – 105
(d) 50 – (-40) – (-2)
= 50 + 40 + 2
= 92