BT1; Tính
a,\(\frac{-5}{7}\)+\(\frac{2}{7}\)+\(\frac{4}{-9}\)+\(\frac{4}{9}\)
b,(\(\frac{1}{2}\):\(\frac{3}{4}\))2
c,\(\frac{1}{2}\)+\(\frac{3}{4}\)-(\(\frac{4}{5}\)+\(\frac{3}{4}\))
d,56:54+23.22-225:152
e,\(\frac{7}{23}\)+\(\frac{4}{17}\)-\(\frac{7}{23}\)+\(\frac{13}{17}\)
g,19\(\frac{1}{4}\).\(\frac{7}{12}\)-15\(\frac{1}{4}\).\(\frac{7}{12}\)