с * 5 + 2,859 = 3,454
с*5=3,454-2,859
с*5 = 0,595
с= 0,595 : 5
с=0,119
18,512 - а*3 = 17,732
а*3 = 18,512 - 17,732
а*3 = 0,78
а= 0,78 : 3
а=0,26
