Tính giá trị các biểu thức sau: a) A = [(-0,5) - 3/5] : (-3) + 1/3 - (-1/6) : (-2)

* Hướng dẫn giải

a) $A=\left[\left(-0,5\right)-\frac{3}{5}\right]:\left(-3\right)+\frac{1}{3}-\left(-\frac{1}{6}\right):\left(-2\right)$

$A=\left[\frac{-1}{2}-\frac{3}{5}\right]:\left(-3\right)+\frac{1}{3}-\frac{-1}{6}.\frac{1}{-2}$

$A=\left[\frac{-5}{10}-\frac{6}{10}\right]:\left(-3\right)+\frac{1}{3}-\frac{1}{12}$

$A=\frac{-11}{10}.\frac{1}{-3}+\frac{1}{3}-\frac{1}{12}$

$A=\frac{11}{30}+\frac{1}{3}-\frac{1}{12}$

$A=\frac{37}{60}$

Vậy $A=\frac{37}{60}$

b) $B=\left(\frac{2}{25}-0,036\right):\frac{11}{50}-\left[\left(3\frac{1}{4}-2\frac{4}{9}\right)\right].\frac{9}{29}$

$B=\left(\frac{2}{25}-\frac{9}{250}\right):\frac{11}{50}-\left[\left(\frac{13}{4}-\frac{22}{9}\right)\right].\frac{9}{29}$

$B=\left(\frac{20}{250}-\frac{9}{250}\right):\frac{11}{50}-\left[\left(\frac{117}{36}-\frac{88}{36}\right)\right].\frac{9}{29}$

$B=\frac{11}{250}:\frac{11}{50}-\frac{29}{36}.\frac{9}{29}$

$B=\frac{11}{250}.\frac{50}{11}-\frac{9}{36}$

$B=\frac{1}{5}-\frac{1}{4}$

$B=\frac{4}{20}-\frac{5}{20}=\frac{-1}{20}$