Tính bằng hai cách: 27,29 - 14,43 - 2,5 ; 29,82 - (11,6 + 10,3)

* Hướng dẫn giải

$27,29-14,43-2,5$

Cách 1:

$\begin{array}{l}\underset{}{\underbrace{27,29-14,4}}3-2,5\\ =12,86-2,5\\ =10,36\end{array}$

Cách 2:

$\begin{array}{l}27,29-14,43-2,5\\ =27,29-\underset{}{\underbrace{\left(14,43+2,5\right)}}\\ =27,29-16,93\\ =10,36\end{array}$

$29,82-\left(11,6+10,3\right)$

Cách 1: 

$\begin{array}{l}29,82-\underset{}{\underbrace{\left(11,6+10,3\right)}}\\ =29,82-21,9\\ =7,92\end{array}$

Cách 2:

$\begin{array}{l}29,82-\left(11,6+10,3\right)\\ =\underset{}{\underbrace{29,82-11,6}}-10,3\\ =18,22-10,3\\ =7,92\end{array}$