câu 1) 

\(\dfrac{-12}{18}+\left(\dfrac{-21}{35}\right)=\dfrac{-19}{15}\)
câu 2) 

\(-\dfrac{3}{21}+\dfrac{6}{42}=0\)
câu 3)

\(-\dfrac{18}{24}+\dfrac{15}{21}=-\dfrac{1}{28}\)
câu 4) 

\(\dfrac{1}{6}+\dfrac{2}{5}=\dfrac{17}{30}\)
câu 5) 

\(\dfrac{3}{5}+\left(-\dfrac{7}{4}\right)=-\dfrac{23}{20}\)
câu 6) 

\(\left(-2\right)+\left(\dfrac{-5}{8}\right)=\dfrac{-21}{8}\)
câu 7) 

\(\dfrac{1}{-8}+\left(-\dfrac{5}{9}\right)=-\dfrac{49}{72}\)
câu 8) 

\(\dfrac{4}{13}+\dfrac{12}{39}=\dfrac{8}{13}\)
câu 9) 

\(\dfrac{1}{21}+\dfrac{1}{28}=\dfrac{1}{12}\)
câu 10) 

\(-\dfrac{3}{29}+\dfrac{16}{58}=\dfrac{5}{29}\)
câu 11) 

\(\dfrac{8}{40}+\left(-\dfrac{36}{45}\right)=-\dfrac{3}{5}\)
câu 12) 

\(-\dfrac{8}{18}+\left(-\dfrac{15}{27}\right)=-1\)
câu 13) 

\(\dfrac{13}{30}+\left(-\dfrac{1}{5}\right)=\dfrac{7}{30}\)
câu 14) 

\(\dfrac{2}{21}+\dfrac{1}{28}=\dfrac{11}{84}\)
câu 15) 

\(5+\left(-\dfrac{3}{4}\right)=\dfrac{17}{4}\)
câu 16) 

\(\dfrac{18}{24}+\dfrac{45}{-10}=-\dfrac{15}{4}\)

18+(-6)+23+(-7)-5=[18+(-6)]+23+[(-7)-5]

                             =12+23+(-12)=23

\

bn giúp mk câu còn lại nữa nha

\(\frac{45+16-17}{45x15+18}\)

=\(\frac{44}{693}\)

=\(\frac{4}{63}\)

\(x+\frac{16}{49}+x+\frac{18}{47}=x+\frac{20}{45}-1\)

\(2x+\frac{16}{49}+\frac{18}{47}-x-\frac{20}{45}=-1\)

\(x+\frac{5494}{20727}=-1\)

\(x=-1-\frac{5494}{20727}=-\frac{26221}{20707}\)

(x+16)/49.... cơ Dung à 

300

465 

ko phải toán lớp 6

5) 24*(15+49)+12*(50+42)

=24*64+12*92

=24*64+12*2*46

=24*64+24*46

=24*(64+46)

=24*110

=2640

a: \(45\cdot\left(-24\right)+\left(-10\right)\cdot\left(-12\right)\)

\(=-45\cdot24+10\cdot12\)

=-1080+120=-960

b: \(\left(-134\right)+51\cdot134+\left(-134\right)\cdot48\)

\(=134\left(-1+51-48\right)\)

\(=134\cdot2=268\)

c: \(\left(-41\right)\cdot\left(59+2\right)+59\left(41-2\right)\)

\(=-41\cdot59-41\cdot2+59\cdot41-59\cdot2\)

\(=-41\cdot2-59\cdot2=-100\cdot2=-200\)

d: \(369\cdot\left(-2\right)-41\cdot82\)

\(=41\cdot\left(-18\right)-41\cdot82\)

\(=41\left(-18-82\right)=41\cdot\left(-100\right)=-4100\)

e: \(\left(135-35\right)\cdot\left(-37\right)+37\left(-42-58\right)\)

\(=100\cdot\left(-37\right)+37\cdot\left(-100\right)\)

=-3700-3700=-7400