a) 4/7 + 6/11 + 7/13 +3/7 + 16/11 + 19/13
=(4/7 + 3/7) + (6/11+16/11) + (7/13+19/13)
=7/7+22/11+26/13 = 1+2+2=5
b) chuyển hỗn số thành phân số rồi tính như câu a
c)3/10 + 2/10 x 3/7 +2/10 x 4/7
=3/10+ 2/10 x (3/7+4/7)
=3/10 + 2/10 x 1=3/10+2/10=5/10=1/2
d) tương tự câu c
a) Ta có: \(\dfrac{4}{7}+\dfrac{6}{11}+\dfrac{7}{13}+\dfrac{3}{7}+\dfrac{16}{11}+\dfrac{19}{13}\)
\(=\left(\dfrac{4}{7}+\dfrac{3}{7}\right)+\left(\dfrac{7}{13}+\dfrac{19}{13}\right)+\left(\dfrac{6}{11}+\dfrac{16}{11}\right)\)
\(=1+2+2\)
=5
b) Ta có: \(7\dfrac{2}{5}+8\dfrac{4}{9}+2\dfrac{3}{5}-3\dfrac{4}{9}\)
\(=\dfrac{37}{5}+\dfrac{13}{5}+\dfrac{76}{9}-\dfrac{31}{9}\)
=10+5
=15
c) Ta có: \(\dfrac{3}{10}+\dfrac{2}{10}\cdot\dfrac{3}{7}+\dfrac{2}{10}\cdot\dfrac{4}{7}\)
\(=\dfrac{3}{10}+\dfrac{2}{10}\)
\(=\dfrac{1}{2}\)
d) Ta có: \(1\dfrac{4}{7}+\dfrac{3}{7}\cdot\dfrac{1}{5}+\dfrac{3}{7}\cdot\dfrac{4}{5}\)
\(=\dfrac{11}{7}+\dfrac{3}{7}\)
=2
