47)
a) \(\dfrac{-3}{7}+\dfrac{5}{13}+\dfrac{-4}{7}\)
\(=\dfrac{-3}{7}+\dfrac{-4}{7}+\dfrac{5}{13}\\ =\dfrac{-7}{7}+\dfrac{5}{13}\\ =\dfrac{-13}{13}+\dfrac{5}{13}\\ =\dfrac{-8}{13}\)
b) \(\dfrac{-5}{21}+\dfrac{-2}{21}+\dfrac{8}{24}\\ =\dfrac{-7}{21}+\dfrac{1}{3}\\ =\dfrac{-1}{3}+\dfrac{1}{3}\\ =0\)
48/28
a) 1/12 + 2/12 = 3/12 = 1/4
b) 4/12 + 2/12 = 6/12 = 1/2
c) 5/12 + 2/12 = 7/12
5/12 +212+ 1/12 = 8/12 = 2/3
5/12 + 4/12 = 9/12 = 3/ 4
5/12 + 4/ 12 + 1/ 12 = 10/ 12 = 5/6
5/12 + 4/12 + 2/ 12 = 11/12
5/12 + 4/12 + 2/ 12 + 1/12 = 12/12.
