=> 0,5.x:5-6,2=7,75-5

=> 0,5.x:5=2,75+6,2

=> 0,5.x=8,95.5

=> x=44,75:0,5

=> x=89,5

x=89,5

\(7,75-\left(0,5.x:5:6,2\right)=5\)

                  \(\left(0,5x:5:6,2\right)=7,75-5\)

               \(\left(0,5.x:6,2\right)=2,75\)

                         \(x:6,2=2,75:0,5\) 

                         \(x:6,2=5,5\)

                         \(x\)     \(=5,5.6,2\)

                         \(x\)       \(=34,1\)

(\(\frac45:\frac65\) + \(\frac15\) : \(\frac{1}{x}\)) x 30 - 26 = 54

(\(\frac45\times\frac56\) + \(\frac15\times x\)) x 30 = 54 + 26

(\(\frac23+\frac15x\)) x 30 = 80

\(\frac23+\frac15x\) = 80 : 30

\(\frac23+\frac15x=\frac83\)

\(\frac15x=\frac83-\frac23\)

\(\frac15x\) = 2

\(x=2:\frac15\)

\(x=2\times5\)

\(x=10\)

Vậy \(x=10\)

6,3 x y + 3,7 x y = 100

y x (6,3 + 3,7) = 100

y x 10 = 100

y = 100 : 10

y = 10

Vậy y = 10

= 1 - 3 + 5 - 7 + 9 - 11 = -6

đùa thui, lm nhah:

( 1 - 3 ) + ( 5 - 7 ) + ( 9 - 11 ) 

= -2 + -2 + -2

= 3 . -2

= -6 

Beep bop bap

S = 1 - 2 + 3 - 4 + ..... + 2013 - 2014 + 2015

S = (1 - 2) + (3 - 4) + .... + (2013 - 2014) + 2015

S = -1 + (-1)  +.... + (-1) + 2015

S = -1 x 1007 + 2015

S = -1007 + 2015 = 1008