27.(-53)+27.(-47)
(47-12)-(47-15)+12
1/2+-2/3

\(\dfrac{-5}{7}\).\(\dfrac{2}{11}\)+\(\dfrac{-5}{7}\).\(\dfrac{9}{11}\)+1

\(\dfrac{5}{13}\)+\(\dfrac{-5}{7}\)+\(\dfrac{-20}{41}\)+\(\dfrac{8}{13}\)+\(\dfrac{-12}{41}\)

cho \(\dfrac{3}{x}\)=\(\dfrac{y}{12}\)=\(\dfrac{3}{4}\) thì giá trị của x và y là:
A.x =4;y =9            B.x =-4;y =-9              C.x =12;y =3                D.x =-12;y =-3

C17: B
C18: D
C19: B
C20: B
C21: A
C22: B

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