31.8 - (1/7+4/7y)=1 2/3y + 4.8
27 - 1/7 - 4/7у = 1 2/3 у
26 6/7 = 4/7у + 1 2/3 у
12/21 у + 1 14/21 у = 26 6/7
2 5/21 у = 26 6/7
у = 188/7 : 47/21 = 188/7 * 21/47 = 12
31.8 - (1/7+4/7y)=1 2/3y + 4.8
27 - 1/7 - 4/7у = 1 2/3 у
26 6/7 = 4/7у + 1 2/3 у
12/21 у + 1 14/21 у = 26 6/7
2 5/21 у = 26 6/7
у = 188/7 : 47/21 = 188/7 * 21/47 = 12