(19 • 700) : 70 – 850+x/18 = 6000 : 50,

13300 : 70 – 850+x/18 = 120,

190 – 850+x/18 = 120 | • 18,

3420 – (850 + x) = 2160,

3420 – 850 – x = 2160,

2570 – x = 2160,

–x = 2160 – 2570,

–x = –410 | • (–1),

x = 410.