1/2 + 1/3 + 1/4 = 6/12 + 4/12 + 3/12 = 13/12
2/3 + 3/4 + 4/5 = 8/12 + 9/12 + 4/5 = 17/12 + 4/5 = 85 / 60 + 48 / 60 = 133/ 60
6/5 + 4/3 + 7/9 = 18/ 15 + 20/15 + 7/9 = 38 /15 + 7/ 9 = 114/45 +35/45 = 149/45
8/9 - 5/6 = 16/18 - 15/18 = 1/18
15/17 - 11 /13 = 195/221 -187/221= 8/221
a) \(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}\)
= \(\frac{6}{12}+\frac{4}{12}+\frac{3}{12}\)
= \(\frac{13}{12}\).
b) \(\frac{2}{3}+\frac{3}{4}+\frac{4}{5}\)
= \(\frac{8}{12}+\frac{9}{12}+\frac{4}{5}\)
= \(\frac{17}{12}+\frac{4}{5}\)
= \(\frac{85}{60}+\frac{48}{60}\)
= \(\frac{133}{60}\).
c)\(\frac{6}{5}+\frac{4}{3}+\frac{7}{9}\)
= \(\frac{54}{45}+\frac{62}{45}+\frac{35}{45}\)
= \(\frac{151}{45}\).
d) \(\frac{8}{9}-\frac{5}{6}\)
= \(\frac{16}{18}-\frac{15}{18}\)
= \(\frac{1}{18}\).
e) \(\frac{15}{17}-\frac{11}{13}\)
= \(\frac{195}{221}\)\(-\frac{187}{221}\)
= \(\frac{8}{221}\).