Bài 26:
a: \(=1+1=2\)
b: \(=\dfrac{6}{12}+\dfrac{8}{16}=\dfrac{1}{2}+\dfrac{1}{2}=1\)
Bài 27: A
Bài 25:
a: \(\dfrac{3}{4}+\dfrac{2}{3}=\dfrac{9+8}{12}=\dfrac{17}{12}\)
3/5+7/10=6/10+7/10=13/10
\(\dfrac{1}{4}+\dfrac{7}{6}=\dfrac{6+28}{24}=\dfrac{34}{24}=\dfrac{17}{12}\)
2/3-2/7=14/21-6/21=8/21

4 và 5