(4,2y - 3.96) * 1.5 = 8.55;

4.2y - 3.96 = 8.55 : 1.5;

4.2y - 3.96 = 5.7;

4.2y = 5.7 + 3.96;

4.2y = 9.66;

y = 9.66 : 4.2;

y = 2.3.