a) 5/7×4/19+2/7-15/19-2021/2022
=20/133+2/7-15/19-2021/2022
=58/133-15/19-2021/2022
=-47/133-2021/2022
=-116199775/85890109
b)5/2/15-7/3/10+1/1/5+1/2/3
=5/2/15-7/3/10+1/3/15+1/10/15
=(5/2/15+1/3/15+1/10/15)-7/3/10
=7/15/15-7/3/10
=7/10
c)47/53×(17/3-53/47)+17(6/17-47/53)
=47/53×640/141+17×(-481/901)
=640/159-481/53
=-803/159
CHÚC BẠN HỌC TỐT!