\(\frac{x}{2}=\frac{\frac{y}{3}}{2}=\frac{z}{\frac{4}{3}}=\frac{x-y}{2-\frac{3}{2}}=\frac{15}{\frac{1}{2}}=30\Leftrightarrow x=2.30=45;z=\frac{4}{3}.30=40\)

vừa mới đi học về mà ..................

bài toán này khó quá , ủng hộ mình nha

có ai giúp tôi ko?

a)y:0,01=285:10

=>y=\(\frac{285:10}{0,01}\)=2850

b)\(\frac{1}{4}\times y=3-\frac{2}{5}\)

=>\(\frac{1}{4}\times y=\frac{13}{5}\)

=>y=\(\frac{13}{5}:\frac{1}{4}=\frac{13}{5}\times4=\frac{52}{5}\)

c)\(\frac{7}{3}:y=\frac{14}{15}\)

=>\(y=\frac{7}{3}:\frac{14}{15}=\frac{7}{3}\times\frac{14}{15}\)

=>y=\(\frac{98}{45}\)

Ta có:

\(\frac{5}{7}+\frac{2}{3}.x=\frac{3}{11}\)

\(\Rightarrow\frac{2}{3}.x=\frac{3}{11}-\frac{5}{7}\)

\(\Rightarrow\frac{2}{3}.x=-\frac{34}{77}\)

\(\Rightarrow x=-\frac{34}{77}:\frac{2}{3}\)

\(\Rightarrow x=-\frac{34}{77}.\frac{3}{2}\)

\(\Rightarrow x=-\frac{13}{11}\)

Ta có:

\(-\frac{22}{15}.x+\frac{1}{3}=\left|-\frac{2}{3}+\frac{1}{5}\right|\)

\(\Rightarrow-\frac{22}{15}.x+\frac{1}{3}=\left|-\frac{7}{15}\right|\)

\(\Rightarrow-\frac{22}{15}.x+\frac{1}{3}=\frac{7}{15}\)

\(\Rightarrow-\frac{22}{15}.x=\frac{7}{15}-\frac{1}{3}\)

\(\Rightarrow-\frac{22}{15}.x=\frac{2}{15}\)

\(\Rightarrow x=\frac{2}{15}:-\frac{22}{15}\)

\(\Rightarrow x=\frac{2}{15}.-\frac{15}{22}\)

\(\Rightarrow x=-\frac{1}{11}\)

Ta có :

\(\frac{1}{3}+\frac{1}{2}:x=-4\)

\(\Rightarrow\frac{1}{2}:x=-4-\frac{1}{3}\)

\(\Rightarrow\frac{1}{2}:x=-\frac{13}{3}\)

\(\Rightarrow x=\frac{1}{2}:-\frac{13}{3}\)

\(\Rightarrow x=-\frac{3}{26}\)

\(\frac{1}{4}+\frac{3}{5}=\frac{17}{20}\)

\(\frac{5}{2}+\frac{7}{9}=\frac{59}{18}\)

\(\frac{3}{2}+\frac{2}{3}=\frac{13}{6}\)

\(\frac{4}{5}+\frac{3}{2}=\frac{23}{10}\)

\(\frac{4}{5}+\frac{3}{15}=\frac{4}{5}+\frac{1}{5}=1\)

\(\frac{2}{3}+\frac{32}{24}=\frac{2}{3}+\frac{4}{3}=2\)

\(\frac{5}{6}+\frac{15}{18}=\frac{5}{6}+\frac{5}{6}=\frac{10}{6}=\frac{5}{3}\)

\(\frac{8}{15}+\frac{2}{3}=\frac{8}{15}+\frac{10}{15}=\frac{18}{15}=\frac{6}{5}\)

\(\frac{3}{7}+\frac{4}{8}=\frac{24}{56}+\frac{28}{56}=\frac{52}{56}=\frac{13}{14}\)

_HT_

Murad trả lời đúng rồi đó! 

a) \(\dfrac{3}{5}-\dfrac{3}{5}.\dfrac{2}{3}=\dfrac{3}{5}-\left(\dfrac{3}{5}.\dfrac{2}{3}\right)=\dfrac{3}{5}-\dfrac{2}{5}=\dfrac{1}{5}\) 

b) \(\dfrac{-7}{9}.\dfrac{11}{15}-\dfrac{4}{15}.\dfrac{-7}{9}-\dfrac{7}{9}=\dfrac{-7}{9}.\left(\dfrac{11}{15}-\dfrac{4}{15}\right)-\dfrac{7}{9}=\dfrac{-7}{9}.\dfrac{7}{15}-\dfrac{7}{9}=-\dfrac{49}{135}-\dfrac{7}{9}=-\dfrac{154}{135}\)

d) \(3\dfrac{1}{7}-\left(4\dfrac{1}{2}+5\dfrac{3}{7}\right)=\dfrac{22}{7}-\left(\dfrac{9}{2}+\dfrac{38}{7}\right)=\dfrac{22}{7}-\left(\dfrac{63}{14}+\dfrac{76}{14}\right)=\dfrac{22}{7}-\dfrac{139}{14}=\dfrac{44}{14}-\dfrac{139}{14}=-\dfrac{95}{14}\)

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CÁC EM  TỰ LÀ ĐI MẤY BÀI NÀY DỄ LĂM CHỊ  HỌC LỚP 8 NÊN CHỊ BIẾT NHƯNG ĐỪNG BẢO CHỊ LÀ CHO HAY GỢI Ý CÁCH LÀM NHA.

tìm y: 

y  x 4 - 25 dm = 75 cm