a) Ta có: \(\left(-2.5\cdot0.38\cdot0.4\right)-\left[0.125\cdot3.15\cdot\left(-8\right)\right]\)
\(=\left(-1\cdot0.38\right)-\left[-1\cdot3.15\right]\)
\(=-0.38+3.15\)
\(=\dfrac{277}{100}\)
b) Ta có: \(\left[\left(-20.83\right)\cdot0.2+\left(-9.17\right)\cdot0.2\right]:\left[2.47\cdot0.5-\left(-3.53\right)\cdot0.51\right]\)
\(=\dfrac{0.2\left(-20.83-9.17\right)}{3.0353}\)
\(=\dfrac{0.2\cdot\left(-30\right)}{3.0353}=\dfrac{-60000}{30353}\)