Thực hiện phép tính (tính hợp lí nếu có thể):

a) \({7^{50}}:{7^{48}} - \left( {{6^2} + {{2024}^0}} \right)\)

\( = {7^2} - \left( {36 + 1} \right)\)

\( = 49 - 37\)

\( = 12\).

b) \(\left( { - 25} \right) + 15 + \left( { - 17} \right) - \left( { - 25} \right) + \left( { - 13} \right)\)

\[ = \left[ {\left( { - 25} \right) + 25} \right] + \left[ {\left( { - 17} \right) + \left( { - 13} \right)} \right] + 15\]

\[ = 0 + \left( { - 30} \right) + 15\]

\( =  - 15\).

c) \(\left( { - 125} \right).5.\left( { - 16} \right).\left( { - 8} \right)\)

\( = \left[ {\left( { - 125} \right).\left( { - 8} \right)} \right].\left[ {5.\left( { - 16} \right)} \right]\)

\[ = 1000.\left( { - 80} \right)\]

\( =  - 80\,\,000\).

d) \(27.121 - 87.27 + 73.34\)

\( = 27.\left( {121 - 87} \right) + 73.34\)

\( = 27.34 + 73.34\)

\( = 34.\left( {27 + 73} \right)\)

\( = 34.100\)

\( = 3400\).