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Each point: 1 Mark
(i) $-87+55=-32$
$\Rightarrow 32m\text{below the water surface}$
(ii) $+98-115=-17$
$\Rightarrow 17m\text{below the water surface}$
(ii) $+36+57-73=20$
$\Rightarrow 20m\text{above the water surface}$
(iv) $-42-23+39=-26$
$\Rightarrow 26m\text{below the water surface}$

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Each option:1 Mark
a. +200m
b. 0
c. -100m

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Each option: 1 Mark
$\text{(a). Let the integer be x}\Rightarrow -25+x=94\Rightarrow x=94+25\Rightarrow x=119$
$\text{(b). Let the integer be x}\Rightarrow 80+x=-320\Rightarrow x=-320-80\Rightarrow x=-400$
$\text{(c). Let the integer be x}\Rightarrow -50+x=100\Rightarrow x=100+50\Rightarrow x=150$
$\text{(d). Let the integer be x}\Rightarrow -70+x=-660\Rightarrow x=-660+70\Rightarrow x=-590$

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Each option: 1 Mark
(a) We first move to the right of 0 by 5 steps reaching 5. Then we move 3 steps to the left of 5 reaching 2.

We get, $(+5)+(-3)=2$
(b)We want to know an integer which is 5 less than 3 for that we need to start from 3 and move to the left by 5 steps and obtain –2 as shown below:

(c)We want to know the integer which is 4 more than –1. So, we start from –1 and proceed 4 steps to the right of –1 to reach 3 as shown below:

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Each option: 1 Mark
(a). $(-3)\times (-3)\times (-3)$
$\Rightarrow 9\times (-3)$
$\Rightarrow -27$
(b). $\left(32\right)\times (-3)\times \left(2\right)\times (-10)$
$\Rightarrow (-96)\times 2\times (-10)$
$\Rightarrow (-192)\times (-10)$
$\Rightarrow 1920$
(c). $(-8)\times \left(0\right)\times (-4)\times \left(18\right)=0$
(d). $(-2)\times (-3)\times (-4)\times (-5)$
$\Rightarrow 6\times 20$
$\Rightarrow 120$

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Each option: 1 Mark
(a). $-10$
(b). $+5$
(c). $+500$
(d). $-200$

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Each option: 1Mark
(i)Lossof Rs 1000
(ii)Losing a weight of 5 kg
(iii)Withdrawal ofRs 500

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Definition: 1 Mark
Integers are a collection of natural numbers, zero and negativeof natural numbers.
e.g. ....-3,-2,-1,0,1,2,3.........

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Each option: 1 Mark
(a). $[15+(-5\left)\right]+[15+(-7\left)\right]$
$\Rightarrow 10+8$
$\Rightarrow 18$
(b). $[34+(-20\left)\right]+[16+(-10\left)\right]$
$\Rightarrow 14+6$
$\Rightarrow 20$
(c). $[32+16]+[9+(-70\left)\right]$
$\Rightarrow [48+(-61\left)\right]$
$\Rightarrow 48-61$
$\Rightarrow -13$
(d). $[-3+(-2\left)\right]+\left[\right(-5)+7]$
$\Rightarrow -5+2$
$\Rightarrow -3$

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Each option: 1 Mark
(i) Final temperature
$\Rightarrow 0^{\circ }C+(+{25}^{\circ }C)+(-{32}^{\circ }C)$
$\Rightarrow 0^{\circ }C+{25}^{\circ }C-{32}^{\circ }C$
$\Rightarrow -7^{\circ }C$
(ii) Final temperature
$\Rightarrow -{20}^{\circ }C+(+{25}^{\circ }C)+(-{32}^{\circ }C)$
$\Rightarrow -{20}^{\circ }C+{25}^{\circ }C-{32}^{\circ }C$
$\Rightarrow -{27}^{\circ }C$