tính nhanh
a) \(\frac{3}{11}\)x \(\frac{7}{25}\)+ \(\frac{15}{11}\)x \(\frac{1}{5}\)
b) \(\frac{3}{7}\)x \(\frac{25}{19}\)+ \(\frac{1}{7}\)x \(\frac{18}{19}\)
c) \(\frac{6}{7}\)x \(\frac{3}{8}\)+ \(\frac{6}{7}\): \(\frac{8}{5}\)+ \(\frac{6}{7}\)
giải giúp e với e cảm ơn ạ