Rút gọn phân số :
a) \(\dfrac{85-17+34}{51-102}\)
\(=\dfrac{102}{-51}=-2\)
b) \(\dfrac{-13.6+12.5}{6\left(-7\right)-\left(-4\right).6}\)
\(=\dfrac{-78+60}{6\left[\left(-7\right)-\left(-4\right)\right]}\)
\(=\dfrac{-18}{-18}=1\)
c) \(\dfrac{2^4.5^2.7}{2^3.5.7^2.11}\)
\(=\dfrac{2^4}{2^3}.\dfrac{5^2}{5}.\dfrac{7}{7^2}.11\)
\(=2.5.\dfrac{1}{7}.11\)
\(=15\dfrac{5}{7}=\dfrac{110}{7}\)