1. Find
(a)
(b)
(c)
(d)
(e)
(f)
It is known that the sum of .
So, we have to split the number in order to cancel out with other numbers.
(a)
= 15 + (- 20) + 20
= 15 + 0 = 15
(b)
= 72 - (72) - 18
= 0 - 18 = -18
(c)
= (- 15) + 18
= (- 15) + (15) + 3
= 0 + 3 = 3
(d)
= - (20 + 13 )
= -33
(e)
= 23 + 12
= 35
(f)
= (- 32) + 40
= (- 32) + (32) + 8
= 0 + 8
= 8