a) 16 – 3,8x = 6,31 3,8x = 16 – 6,31 3,8x = 9,69 x = 9,69 / 3,8 x = 2,55
б) 5,4x – 2,6x = 10,84 – 2,3 2,8x = 8,54 x = 8,54 / 2,8 x = 3,05