(7200-а×200)+2000=3400 уравнение
(7200 - a*200) + 2000 = 3400 7200 - a*200 = 3400 - 2000 7200 - a*200 = 1400 - a*200 = 1400 - 7200 - a*200 = - 5800 a*200 = 5800 a = 5800/200 a = 29
7200-a=3400-2000:200 7200-a=1400:200 7200-a=7 a=7200 a=7200-7 a=7193