Câu 1.17 :
1,2. $\frac{15}{4}$+ $\frac{16}{7}$. $\frac{-85}{8}$- 1,2.5$\frac{3}{4}$- $\frac{16}{7}$. $\frac{-71}{8}$= 1,2. ($\frac{15}{4}$-5$\frac{3}{4}$)+ $\frac{16}{7}$. ( $\frac{-85}{8}$+$\frac{-71}{8}$)= 1,2.($\frac{15}{4}$-$\frac{23}{4}$)+$\frac{16}{7}$. ( $\frac{-85}{8}$+$\frac{-71}{8}$) = 1,2. ($\frac{-8}{4}$)+$\frac{16}{7}$.($\frac{-14}{8}$) = 1,2.(-2)-2.2 = -6,4