Tính a) 8/5 + 3/10

a) 8/5 + 3/10 = 16/10 + 3/10 = (16 +3)/10 = 19/10

b) 2/3 + 3/4 + 1/6 = 8/12 + 9/12 + 2/12 = 19/12

c) 5/6 - 2/9 = 15/18 - 4/18 = 11/18

d) 21/10 - 3/4 - 2/5 = 42/20 - 15/20 - 8/20 = 19/20

Giải Luyện tập chung Bài 13 tại: https://vndoc.com/giai-vo-bai-tap-toan-5-bai-13-luyen-tap-chung-147007

a) \(\displaystyle {8 \over 5} + {3 \over {10}} = {{16} \over {10}} + {3 \over {10}} = {{16 + 3} \over {10}} = {{19} \over {10}}\)

b) \(\displaystyle {2 \over 3} + {3 \over 4} + {1 \over 6} = {{8} \over {12}} + {{9} \over {12}} + {{2} \over {12}} \displaystyle = {{8 + 9 + 2} \over {12}} = {{19} \over {12}}\)

c) \(\displaystyle {5 \over 6} - {2 \over 9} = {{15} \over {18}} - {{4} \over {18}} = {{15 - 4} \over {18}} = {{11} \over {18}}\)

d) \(\displaystyle 2{1 \over {10}} - {3 \over 4} - {2 \over 5} = {{21} \over {10}} - {3 \over 4} - {2 \over 5}\)

\(\displaystyle = {{42} \over {20}} - {{15} \over {20}} - {{8} \over {20}} \displaystyle = {{42 - 15 - 8} \over {20}} = {{19} \over {20}}\)