\(15+25+35+...+85+95\)
\(=95+\left(85+15\right)+\left(75+25\right)+\left(65+35\right)+\left(55+45\right)\)
\(=95+100+100+100+100\)
\(=100.4+95\)
\(=400+95\)
\(=495\)

\(\dfrac{3}{2}x+\dfrac{3}{4}=\dfrac{4}{5}-x\)
\(\dfrac{3}{2}x+x=\dfrac{4}{5}-\dfrac{3}{4}\)
\(x\left(\dfrac{3}{2}+1\right)=\dfrac{16}{20}-\dfrac{15}{20}\)
\(x\left(\dfrac{3}{2}+\dfrac{2}{2}\right)=\dfrac{1}{20}\)
\(x.\dfrac{5}{2}=\dfrac{1}{20}\)
\(x=\dfrac{1}{20}:\dfrac{5}{2}\)
\(x=\dfrac{1}{20}.\dfrac{2}{5}\)
\(x=\dfrac{1.1}{10.5}\)
\(x=\dfrac{1}{50}\)
Vậy ....

\(\left(2x-1\right)+\dfrac{1}{4}=75\%\)
\(\left(2x-1\right)+\dfrac{1}{4}=\dfrac{3}{4}\)
\(2x-1=\dfrac{3}{4}-\dfrac{1}{4}\)
\(2x-1=\dfrac{2}{4}\)
\(2x-1=\dfrac{1}{2}\)
\(2x=\dfrac{1}{2}+1\)
\(2x=\dfrac{1}{2}+\dfrac{2}{2}\)
\(2x=\dfrac{3}{2}\)
\(x=\dfrac{3}{2}:2\)
\(x=\dfrac{3}{2}.\dfrac{1}{2}\)
\(x=\dfrac{3}{4}\)
Vậy...

\(2.x-3=5\)
\(2x=5+3\)
\(2x=8\)
\(x=8:2\)
\(x=4\)
Vậy....

\(a,\dfrac{3}{a}-\dfrac{4}{7}=1-\dfrac{34}{35}\)
\(\dfrac{3}{a}-\dfrac{4}{7}=\dfrac{35}{35}-\dfrac{34}{35}\)
\(\dfrac{3}{a}-\dfrac{4}{7}=\dfrac{1}{35}\)
\(\dfrac{3}{a}=\dfrac{1}{35}+\dfrac{4}{7}\)
\(\dfrac{3}{a}=\dfrac{1}{35}+\dfrac{20}{35}\)
\(\dfrac{3}{a}=\dfrac{21}{35}\)
\(\dfrac{3}{a}=\dfrac{3}{5}\)
\(a=5\)
Vậy....
\(b,\dfrac{5+a}{12}=\dfrac{2}{3}\)
\(\left(5+a\right).3=2.12\)
\(\left(5+a\right).3=24\)
\(5+a=24:3\)
\(5+a=8\)
\(x=8-5\)
\(x=3\)
Vậy...

Cô ơi, lại có bão mới ạ?:(( Hễ mà còn bão thì chúc các bạn ở vùng bão hoặc chịu ảnh hưởng của bão luôn luôn an toàn ạ :((

\(x-\left(\dfrac{1}{3}+\dfrac{1}{5}-\dfrac{1}{7}\right)=\dfrac{1}{7}-\dfrac{1}{3}\)
\(x-\left(\dfrac{35}{105}+\dfrac{21}{105}-\dfrac{15}{105}\right)=\dfrac{3}{21}-\dfrac{7}{21}\)
\(x-\dfrac{41}{105}=\dfrac{-4}{21}\)
\(x=\dfrac{-4}{21}+\dfrac{41}{105}\)
\(x=\dfrac{-20}{105}+\dfrac{41}{105}\)
\(x=\dfrac{21}{105}=\dfrac{1}{5}\)
\(2x-\left(\dfrac{1}{4}+\dfrac{3}{5}-\dfrac{1}{9}\right)=\dfrac{1}{9}-\dfrac{1}{4}\)
\(2x-\left(\dfrac{45}{180}+\dfrac{108}{180}-\dfrac{20}{180}\right)=\dfrac{4}{36}-\dfrac{9}{36}\)
\(2x-\dfrac{133}{180}=\dfrac{-5}{36}\)
\(2x=\dfrac{-5}{36}+\dfrac{133}{180}\)
\(2x=\dfrac{-25}{180}+\dfrac{133}{180}\)
\(2x=\dfrac{108}{180}\)
\(2x=\dfrac{3}{5}\)
\(x=\dfrac{3}{5}:2\)
\(x=\dfrac{3}{5}.\dfrac{1}{2}\)
\(x=\dfrac{3}{10}\)
 

\(96+4.\left(27-2x\right)=196\)
\(4\left(27-2x\right)=196-96\)
\(4\left(27-2x\right)=100\)
\(27-2x=100:4\)
\(27-2x=25\)
\(2x=27-25\)
\(2x=2\)
\(x=2:2\)
\(x=1\)
Vậy \(x=1\)

Nó sẽ khác nhé.
Beautiful đổi sang so sánh hơn sẽ là more beautiful nha

Đề bài hình như sai ạ.