$50-(-40)-(-2)=50+40+2=92$

$(-3)-(-4)=-3+4=+1(-4)+(-3)=-4-3=-7$
Since $+1>-7$, $(-3)-(-4)>(-4)+(-3)$

$(-8)-7-(+6)-5-(-4)-3-2-(-1)-0=-8-7-6-5+4-3-2+1=-26+4-5+1=-26+5-5=-26$

-9-(-10) = -9+10

=> Move 10 steps towards right from -9 and you will reach +1.  

-50 + 45 + (-145)

= -50 + 45 - 145

= 45+(-195) = -150

$(-12)+\left(12\right)+(-6)+(-5)+(-7)+(-10)$
$=(-12)+\left(12\right)+(-28)$
$=0-28$
$=-28$

(+12)+(-4) = 12 - 4 = 8

According to the problem,
There are 4 black buttons = -4
There are 3 white buttons = 3
So, we can write in mathematical form, we get
= (-4) + (+3)
= - 4 + 3 
=  -1 
Thus, the net value of all the buttons is -1.

 -12 + 14 = +2.

 So, +2 is 14 more than -12.

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