Tính hợp lý (nếu có thể): - 77 + 57 - 80

a) \( - 77 + 57 - 80\)

\( = - 20 - 80\)

\( = - 100\)

b)\(58 \cdot 19 + 58 \cdot \left( { - 119} \right)\)

\[ = 58\left[ {19 + \left( { - 119} \right)} \right]\]

\[ = 58.\left( { - 100} \right)\]\[ = - 5800\]

c) \[\left[ {{3^5}:{3^2} + \left( { - 20} \right)} \right] \cdot {2024^0} - \left( {15 \cdot 3 - 21} \right):{2^2}\]

\[ = \left[ {{3^3} + \left( { - 20} \right)} \right] \cdot 1 - \left( {45 - 21} \right):4\]  

\[ = \left( {27--20} \right) \cdot 1-24:4\]

\[ = 7-6 = 1\].