So sánh các phân số:

a,\(\dfrac{1}{5}và\dfrac{3}{5}\)                    b\(\dfrac{8}{21}và\dfrac{8}{9}\)                  c,\(\dfrac{3}{5}và1\)            d,\(\dfrac{7}{5}và1\)

a,\(\dfrac{1}{7}\text{x}\dfrac{2}{7}+\dfrac{1}{7}\text{x}\dfrac{5}{7}+\dfrac{6}{7}\)            b,\(\dfrac{6}{11}\text{x}\dfrac{4}{9}+\dfrac{6}{11}\text{x}\dfrac{7}{9}-\dfrac{6}{11}\text{x}\dfrac{2}{9}\)

c, \(\dfrac{4}{25}\text{x}\dfrac{5}{8}\text{x}\dfrac{25}{4}\text{x}24\)