Thực hiện phép tính (tính hợp lí nếu có thể):a) 5/1/3 - 2/1/3; b) (–4,44 + 60 – 5,56) : (1,2 – 0,8);

Hướng dẫn giải:

a) \(5\frac{1}{3} - 2\frac{1}{3}\)

\( = \left( {5 + \frac{1}{3}} \right) - \left( {2 + \frac{1}{3}} \right)\)

\( = 5 + \frac{1}{3} - 2 - \frac{1}{3}\)

\( = \left( {5 - 2} \right) + \left( {\frac{1}{3} - \frac{1}{3}} \right)\)

= 3

b) (–4,44 + 60 – 5,56) : (1,2 – 0,8)

= [60 + (– 4,44 – 5,56)] : 0,4

= [60 + (–10)] : 0,4

= 50 : 0,4

= 125.

c) \(1\frac{{13}}{{15}}.0,75 - \left( {\frac{8}{{15}} + 25\% } \right)\)

\( = \frac{{28}}{{15}}.\frac{{75}}{{100}} - \left( {\frac{8}{{15}} + \frac{{25}}{{100}}} \right)\)

\[ = \frac{{4.7}}{{3.5}}.\frac{{3.25}}{{4.25}} - \left( {\frac{8}{{15}} + \frac{1}{4}} \right)\]

\( = \frac{7}{5} - \frac{8}{{15}} - \frac{1}{4}\)

\( = \frac{{84}}{{60}} - \frac{{32}}{{60}} - \frac{{15}}{{60}}\)

\( = \frac{{37}}{{60}}\)