Question

giúp em với ạ. em cần gấp. camon

Tính bằng cách hợp lí:

a, 2 - (\(\dfrac{3}{7}\)+\(\dfrac{1}{3}\)) - (2- \(\dfrac{4}{3}\)+\(\dfrac{2}{7}\)) + 2 - (4-\(\dfrac{5}{7}\))

b, \(\dfrac{-3}{13}\) . (\(\dfrac{44}{33}\)+\(\dfrac{4444}{3030}\)+\(\dfrac{444444}{404040}\))