Thực hiện phép tính (tính hợp lí nếu có thể): a) - 5/8 . - 12/29 . 8/ - 10 . 2,9

a) \(\frac{{ - 5}}{8} \cdot \frac{{ - 12}}{{29}} \cdot \frac{8}{{ - 10}} \cdot 2,9\)

\( = \frac{{ - 5}}{8} \cdot \frac{{ - 6 \cdot 2}}{{29}} \cdot \frac{8}{{ - 5 \cdot 2}} \cdot \frac{{29}}{{10}}\)

\( = \frac{{ - 6}}{{10}} =  - \frac{3}{5}.\)

b) \(\left( { - 1,6} \right) \cdot \left( { - 0,125} \right) \cdot \left( { - 0,5} \right)\)

\( = 0,2 \cdot \left( { - 0,5} \right)\)

\( =  - 0,1.\)

c) \[19\frac{5}{8}:\frac{7}{{12}} - 15\frac{1}{4}:\frac{7}{{12}}\]

\[ = \frac{{157}}{8} \cdot \frac{{12}}{7} - \frac{{61}}{4} \cdot \frac{{12}}{7}\]

\[ = \left( {\frac{{157}}{8} - \frac{{61}}{4}} \right) \cdot \frac{{12}}{7}\]

\[ = \frac{{35}}{8} \cdot \frac{{12}}{7} = \frac{{15}}{2}.\]

d) \(1,9 + \left( {2,51 - 2,13 \cdot 4} \right) - \left( {96 \cdot 2,13 - 99 \cdot 2,51} \right)\)

\( = 1,9 + 2,51 - 2,13 \cdot 4 - 96 \cdot 2,13 + 99 \cdot 2,51\)

\( = \left( {2,51 + 99 \cdot 2,51} \right) - \left( {2,13 \cdot 4 + 96 \cdot 2,13} \right) + 1,9\)

\( = 2,51 \cdot \left( {1 + 99} \right) - 2,13 \cdot \left( {4 + 96} \right) + 1,9\)

\( = 2,51 \cdot 100 - 2,13 \cdot 100 + 1,9\)

\( = 251 - 213 + 1,9\)

\( = 38 + 1,9\)

\( = 39,9.\)