12.5 . -5/7 + 9 3/4 - 1.5 . 5/7
\(=\frac{5}{7}.\left(-60\right)+\frac{39}{4}-5.\frac{5}{7}\)
\(=\frac{5}{7}.\left[\left(-60\right)-5\right]+\frac{39}{4}\)
\(=\frac{5}{7}.\left(-65\right)+\frac{39}{4}\)
\(=\frac{-325}{7}+\frac{39}{4}=\frac{-1027}{28}\)
học tốt
= 25/2 . -5/7+ 39/4 + -3/2 . 5/7 = -125/14 + 39/4 + -15/14 = ( -125/14 + -15/14 ) + 39/4 = -10 + 39/4 = -1/4