Tính (theo mẫu).
Mẫu: \(\displaystyle2 - {3 \over 2} = {4 \over 2} - {3 \over 2} = {1 \over 2}\)
a) \(\displaystyle4 - {8 \over 5}\) b) \(\displaystyle{{16} \over 7} - 2\)
c) \(\displaystyle2 - {3 \over 8}\) d) \(\displaystyle{{25} \over 4} - 3\)
a) \(\displaystyle4 - {8 \over 5} = {{20} \over 5} - {8 \over 5} = {{20 - 8} \over 5} = {{12} \over 5}\)
b) \(\displaystyle{{16} \over 7} - 2 = {{16} \over 7} - {{14} \over 7} = {{16 - 14} \over 7} \displaystyle= {2 \over 7}\)
c) \(\displaystyle2 - {3 \over 8} = {{16} \over 8} - {3 \over 8} = {{16 - 3} \over 8} = {{13} \over 8}\)
d) \(\displaystyle{{25} \over 4} - 3 = {{25} \over 4} - {{12} \over 4} = {{25 - 12} \over 4} \displaystyle= {{13} \over 4}\)
-- Mod Toán lớp 4