a: -26-(x-7)=0

=>x-7=-26

=>x=-26+7=-19

b: \(24-\left(30+x\right)=-7\)

=>\(30+x=24-\left(-7\right)\)

=>\(x+30=24+7=31\)

=>x=31-30=1

c: \(3-\left(17-x\right)=-12\)

=>\(17-x=3-\left(-12\right)\)

=>\(17-x=3+12=15\)

=>x=17-15=2

d: \(\left(5-x\right)-7=-15\)

=>\(5-x=-15+7=-8\)

=>\(x=5-\left(-8\right)=5+8=13\)

a) |-2-x|=-15+37         

|-2-x|=22

x=22+(-2)

x=20

Bài 2:

a: Ta có: \(2x+79=x+45\)

nên 2x-x=45-79

hay x=-24

b: Ta có: \(15-\left(x+7\right)=\left(x-8\right)+22\)

\(\Leftrightarrow8-x-x-14=0\)

\(\Leftrightarrow2x=22\)

hay x=11

a, \(x\) - \(\dfrac{2}{7}\) = \(\dfrac{4}{5}\) \(\times\) \(\dfrac{15}{24}\)

    \(x\) - \(\dfrac{2}{7}\) = \(\dfrac{1}{2}\)

    \(x\)        = \(\dfrac{1}{2}\) + \(\dfrac{2}{7}\)

    \(x\)       = \(\dfrac{11}{14}\)

b, \(x\): \(\dfrac{2}{7}\) = \(\dfrac{9}{8}\) - \(\dfrac{15}{6}\)

     \(x\):  \(\dfrac{2}{7}\) = - \(\dfrac{11}{8}\)

     \(x\)      = - \(\dfrac{11}{8}\) \(\times\) \(\dfrac{2}{7}\)

     \(x\)     = - \(\dfrac{11}{28}\)

a) x = 11/14

b) x = -11/28

\(a,\) \(x\) \(-\) \(\dfrac{2}{7}\) \(=\dfrac{4}{5}\times\dfrac{15}{24}\)

   \(x-\dfrac{2}{7}=\dfrac{1}{2}\)

  \(x\)          \(=\) \(\dfrac{1}{2}+\dfrac{2}{7}\)

 \(x\)           \(=\) \(\dfrac{11}{14}\)

\(b,\) \(x\div\dfrac{2}{7}=\dfrac{9}{8}-\dfrac{15}{6}\)                                               

\(x\div\dfrac{2}{7}=\dfrac{87}{24}\)

\(x=\dfrac{87}{24}\times\dfrac{2}{7}\)

\(x=\dfrac{87}{84}\)

x=2/15:4/15

x=1/2

7/24+x=2-1/4

7/24+x=7/4

x=7/4-7/24

x=42/24-7/24

x=35/24

a \(x=\dfrac{2}{15}:\dfrac{4}{15}\)

\(x=\dfrac{2}{15}\times\dfrac{15}{4}\)

\(x=\dfrac{1}{2}\)

b \(\dfrac{7}{24}+x=\dfrac{7}{4}\)

\(x=\dfrac{7}{4}-\dfrac{7}{24}\)

\(x=\dfrac{42}{24}-\dfrac{7}{24}\)

\(x=\dfrac{35}{24}\)

a)4/15 x x=2/15

=> x = 2/15 : 4/15

=> x = 1/2
b)7/24+x=2-1/4

=> 7/24 + x = 7/4

=> x = 7/4 - 7/24

=> x = 35/24