Tìm x, biết rằng: a) 5/8 x + 2/5 =1/5 b) 5/7 : x + 11/7 = 18/7 c) (2x/5

a) 

58x+25=1558x           =15−2558x          =−15x             =−15:58x              =−15.85x             =−825

b)

57:x+117=18757:x          =187−11757:x           =1x               =57:1x              =57

c)

2x5−1:−5=172x5−1       =17.−52x5−1     =−572x5            =−57+12x5            =25x               =25:25x               =1