\(3\times145+3\times\dfrac{55}{6}\times215+6\times85\)

\(=3\times145+3\times\dfrac{55}{6}\times215+3\times2\times85\)

\(=3\times\left(145+\left(\dfrac{55}{6}\times215\right)+\left(2\times85\right)\right)\)

\(=3\times\left(145+\dfrac{11825}{6}+170\right)\)

\(=3\times\dfrac{13715}{6}=6857,5\)

3*(145+55):6*(215+85)

3*200:6*300

600:6*300

100*300=30000

\(a.\dfrac{11}{10}\text{=}\dfrac{11\times3}{10\times3}\text{=}\dfrac{33}{30}\)

\(\dfrac{19}{30}\) giữ nguyên

\(b.\dfrac{23}{38}\text{=}\dfrac{23\times3}{38\times3}\text{=}\dfrac{69}{114}\)

\(\dfrac{14}{57}\text{=}\dfrac{14\times2}{57\times2}\text{=}\dfrac{28}{114}\)

Sos

a)Số học sinh cả lớp:
\(30+28=58\left(hocsinh\right)\)
Số học sinh nam chiếm:
\(28:58=\dfrac{14}{29}\)(số học sinh cả lớp)
b)Số học sinh nam chiếm:
\(28:30=\dfrac{14}{15}\)(số học sinh nữ)

10/11 nhé

  \(\dfrac{10}{11}\)

 Giải thích:

   \(\dfrac{3465}{3960}\)(\(\dfrac{7}{8}\))<\(\dfrac{3520}{3960}\)(\(\dfrac{8}{9}\))<\(\dfrac{3564}{3960}\)(\(\dfrac{9}{10}\))<\(\dfrac{3600}{3960}\)(\(\dfrac{10}{11}\))

8/10;6/7;16/14;37/35

 \(\dfrac{8}{10}\), \(\dfrac{6}{7}\), \(\dfrac{16}{14}\), \(\dfrac{37}{35}\)

`45 xx 16 xx 4`

`=(45xx4)xx16`

`= 180 xx 16`

`= 2880`

3/5 = 12/20

4/5 =12/15

=> Những phân số bé hơn 4/5 lớn hơn 3/5 có tử số 12 là: 12/16, 12/17, 12/18, 12/19

 \(\dfrac{12}{16}\), \(\dfrac{12}{17}\), \(\dfrac{12}{18}\), \(\dfrac{12}{19}\)