a)-315/540=-7/12
b)25.13/26.35=5.5.13/13.2.5.7=5/2.7=5/14
c)3.13-13.18/15.40-80
=13.(3-18)/40.(15-2)
=13.-15/40.13
=-15/40=-3/8
d)-1997.1996+1/-1995.-1997+1996
=-3986011/3986011
=-1
a) \(\dfrac{-315}{540}=\dfrac{-315:45}{540:45}=\dfrac{-7}{12}\)
b) \(\dfrac{25\cdot13}{26\cdot35}=\dfrac{25}{35}\cdot\dfrac{13}{26}=\dfrac{5}{7}\cdot\dfrac{1}{2}=\dfrac{5}{14}\)
c) \(\dfrac{3\cdot13-13\cdot18}{15\cdot40-80}=\dfrac{13\left(3-18\right)}{40\left(15-2\right)}=\dfrac{-13\cdot15}{40\cdot13}=\dfrac{-15}{40}=-\dfrac{3}{8}\)