a. (-12).73 + 20.(-12) + (-12).7

= (-12).(73+20+7)

= (-12).100

= -1200

b. 15.(-24)+(-24).48-24

= (-24).(15+48+1)

= (-24).64

= -1536

ủa r bài nào?

Ở trong sgk hả?

a 11gioư116 phút

Làm có cần trình bày không ?

có  nhé 

a) 32 giờ 30 phút

b) 10 giờ 30 phút

 NHỚ TÍCH CHO MÌNH NHA

a: \(=\dfrac{-5}{8}+\dfrac{7}{12}=\dfrac{-15}{24}+\dfrac{14}{24}=\dfrac{-1}{24}\)

b: \(=\dfrac{3}{4}-\dfrac{5}{6}+\dfrac{11}{12}=\dfrac{9}{12}-\dfrac{10}{12}+\dfrac{11}{12}=\dfrac{10}{12}=\dfrac{5}{6}\)

c: \(=\dfrac{6}{36}-\dfrac{1}{36}=\dfrac{5}{36}\)

d: \(=\dfrac{5}{12}+\dfrac{5}{12}=\dfrac{10}{12}=\dfrac{5}{6}\)

e: \(=\dfrac{-8}{56}-\dfrac{7}{56}=\dfrac{-15}{56}\)

f: \(=\dfrac{-5}{15}+\dfrac{3}{25}=\dfrac{-25}{75}+\dfrac{9}{75}=\dfrac{-16}{75}\)

a) ( 2011 - 125 x 8 : 4 ) x ( ( 48 : 8 x 6 )

= ( 2011 - 1000 : 4 ) x ( 6 x 6 )

= ( 2011 - 250 ) x 36

= 1761 x 36

= 63396

b) B = Không hiểu

c) C = 

\(\dfrac{2}{5}+\dfrac{1}{3}=\dfrac{6+5}{15}=\dfrac{11}{15}\)

\(\dfrac{16}{24}+\dfrac{1}{3}=\dfrac{2}{3}+\dfrac{1}{3}=1\)

\(\dfrac{7}{12}+\dfrac{4}{6}+\dfrac{3}{8}=\dfrac{14}{24}+\dfrac{16}{24}+\dfrac{9}{24}=\dfrac{39}{24}=\dfrac{13}{8}\)

\(1+\dfrac{1}{12}=\dfrac{12+1}{12}=\dfrac{13}{12}\)

2/5+1/3= 6/15+5/15=11/15

2/5+1/3=11/15

16/24+1/3=1

7/12+4/6+3/8=13/8

1+1/12=13/12

A)4/5x (5/6+1/6)

   4/5x     1= 4/5

\(a,\dfrac{5}{6}\times\dfrac{4}{5}+\dfrac{4}{5}\times\dfrac{1}{6}+\dfrac{4}{5}=\dfrac{4}{5}\times\left(\dfrac{5}{6}+\dfrac{1}{6}+1\right)=\dfrac{4}{5}\times2=\dfrac{8}{5}\)

\(b,60\times\left(\dfrac{105}{180}+\dfrac{48}{180}\right)=60\times\dfrac{17}{20}=51\)

a) \(\dfrac{5}{6}\times\dfrac{4}{5}+\dfrac{4}{5}\times\dfrac{1}{6}+\dfrac{4}{5}\)

\(=\dfrac{5}{6}\times\dfrac{4}{5}+\dfrac{4}{5}\times\dfrac{1}{6}+\dfrac{4}{5}\times1\)

\(=\dfrac{4}{5}\times\left(\dfrac{5}{6}+\dfrac{1}{6}+1\right)\)

\(=\dfrac{4}{5}\times2\)

\(=\dfrac{8}{5}\)

b) \(60\times\left(\dfrac{7}{12}+\dfrac{4}{15}\right)\)

\(=60\times\dfrac{17}{20}\)

\(=\dfrac{1020}{20}\)

\(=51\)