\(\dfrac{4}{1.5}\)+\(\dfrac{4}{5.9}\)+\(\dfrac{4}{9.13}\)+...+\(\dfrac{4}{2017.2021}\)+\(\dfrac{4}{2021.2025}\)
 

5 x 25% + 12 x 30% - 9 x 50%
=5 x 0.25 + 12 x 0.3 - 9 x 0.5
=1.25 + 3.6 - 4.5 
= 4.85 - 4.5 
=0.35

tính hợp lý

(3,8-10,11-\(\dfrac{31}{47}\))-(3,98+29,89-\(\dfrac{31}{47}\))

Tính hợp lí

\(\dfrac{16}{19}\)+\(\dfrac{17}{25}\)+\(\dfrac{22}{19}\)-\(\dfrac{17}{15}\)