a: =>11x-66=4x+11
=>7x=77
hay x=11
b: =>0,25x+1999=53+1999
=>0,25x=53
=>x=53x4=212
`11 . (x-6)= 4.x + 11`
`11x - 66 = 4x + 11`
`(11-4)x = 11 + 66`
`7x = 77`
`=>x=77:7`
`x=11`
________________________________
`( x . 0,25 + 1999) .2000 = (53 + 1999) . 2000`
`x . 0,25 + 1999 = (53 + 1999) . 2000 : 2000`
`x . 0,25 + 1999= 53 + 1999 . 1`
`x . 0,25 + 1999 = 2052`
`x.0,25 = 2052 - 1999`
`x.0.25 = 53`
`x=53 :0,25`
`x=212`