12. (-47) + 12. (-19) + (-66). 88

= 12. [(-47) + (-19)] + (-66). 88

= 12. (-66) + (-66). 88

= (-66). (12 + 88)

= (-66). 100

= -6600

A = 12.(-47) + 12.(-19) + (-66).88

A = -12.(47 + 19)  - 66.88

A = -12.66 - 66.88

A = -66.(12 + 88)

A = -66. 100

A = - 6600

d: \(-37\cdot\left(-19\right)+37\left(-19\right)\)

\(=-19\left(-37+37\right)\)

\(=-19\cdot0=0\)

e: \(\left(29-9\right)\cdot\left(-9\right)+\left(-13-7\right)\cdot21\)

\(=20\cdot\left(-9\right)+\left(-20\right)\cdot21\)

\(=-20\left(9+21\right)\)

\(=-20\cdot30=-600\)

h: \(12\cdot\left(-47\right)+12\left(-19\right)+\left(-66\right)\cdot88\)

\(=12\left(-47-19\right)+\left(-66\right)\cdot88\)

\(=\left(-66\right)\cdot12+\left(-66\right)\cdot88\)

\(=-66\left(12+88\right)\)

\(=-66\cdot100=-6600\)

\(12\cdot\left(-47\right)+12\cdot\left(-19\right)+\left(-66\right)\cdot88\)

\(=12\left(-47-19\right)+\left(-66\right)\cdot88\)

\(=-66\cdot12+88\cdot\left(-66\right)\)

\(=-66\left(12+88\right)\)

\(=-66\cdot100=-6600\)

𝑎=−858

-858

=-858

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92 + 71 + 108 = (92 + 108) + 71 = 200 + 71 = 271

32 x 47 + 53 x 47 + 47 x 15 = 47(32 + 53 + 15)

                                         = 47.100

                                         = 4700

90 x 143 - 43 x 90 = 90.(143 - 43) = 90.100 = 9000

(1200 + 60) : 12 = 1800 : 12 = 150

2 x 18 x 24 + 3 x 50 x 16 + 12 x 32 x 4 = 18.(2.24) + 50.(3.16) + 32.(12.4) = 18.48 + 50.48 + 32.48 = 48(18 + 50 + 32) = 48.100 = 4800

92+71+108=71+92+108=71+200=271

92+71+108=71+(92+108)=71+200=271

90x143-43x90=90x(143-43)=90x100=9000

32x47+53x47+47x15=47x(32+53+15)=47x100=4700

(1200+60):12=1260:12=105

2x18x24+3x50x16+12x32x4=(2x24)x18+(3x16)x50+(12x4)x32

=48x18+48x50+48x32

=48x(18+50+32)

=48x100=4800

C

C

Chọn C