Verified answer

Ответ:

6.75 Ω

Объяснение:

R1,2 = R1 × R2/(R1 + R2) = 5 × 15/(15 + 5) = 75/20 = 3.75 (Ω)

R3 = V/I = 12/4 = 3 (Ω)

R = R1,2 + R3 = 3.75 + 3 = 6.75 (Ω)