a: \(=-12.8\left(34.7+65.3\right)=-12.8\cdot100=-1280\)
b: \(=-\dfrac{3}{7}\left(\dfrac{11}{29}+\dfrac{18}{29}\right)=-\dfrac{3}{7}\)
c: \(=-\dfrac{21}{67}+\dfrac{21}{67}+3+\dfrac{4}{5}+\dfrac{1}{5}=4\)
a) \(\left(-12,8\right)\cdot34,7+\left(-12,8\right)\cdot65,3=\left(-12,8\right)\cdot\left(34,7+65,3\right)=\left(-12,8\right)\cdot100=-1280\)
b) \(\dfrac{-3}{7}\cdot\dfrac{11}{29}+\dfrac{-3}{7}\cdot\dfrac{18}{29}=\dfrac{-3}{7}\cdot\left(\dfrac{11}{29}+\dfrac{18}{29}\right)=\dfrac{-3}{7}\cdot1=\dfrac{-3}{7}\)
c) \(\dfrac{-21}{67}+3\dfrac{4}{5}+\dfrac{21}{67}+\dfrac{1}{5}=\left(\dfrac{-21}{67}+\dfrac{21}{67}\right)+\left(3\dfrac{4}{5}+\dfrac{1}{5}\right)=0+\dfrac{20}{5}=0+4=4\)
