3 + 1/2 (4/5 + 0.6) + 0.5 = 3 + 1/2 (0.8 + 0.6) + 0.5
= 3 + 1/2 * 1.4 + 0.5
= 3 + 0.7 + 0.5
= 4.2

Ответ: 4.2