Rút gọn rồi tính:
a) \(\displaystyle{4 \over 5} + {3 \over {15}}\) b) \(\displaystyle{2 \over 3} + {{32} \over {24}}\) c) \(\displaystyle{5 \over 6} + {{15} \over {18}}\)
a) \(\displaystyle{4 \over 5} + {3 \over {15}} = {4 \over 5} + {1 \over 5} \displaystyle= {5 \over 5} = 1\)
b) \(\displaystyle{2 \over 3} + {{32} \over {24}} = {2 \over 3} + {4 \over 3} = {6 \over 3} = 2\)
c) \(\displaystyle{5 \over 6} + {{15} \over {18}} = {5 \over 6} + {5 \over 6} = {{10} \over {12}} = {5 \over 3}\)
-- Mod Toán lớp 4