1). R₄₅ = R₄R₅/(R₄+R₅) = 150 : 25 = 6 (Ом)
2). R₃₄₅ = R₃ + R₄₅ = 4 + 6 = 10 (Ом)
3). R₃₄₅₆ = R₃₄₅R₆/(R₃₄₅+R₆) = 150 : 25 = 6 (Ом)
4). R₂₃₄₅₆ = R₂ + R₃₄₅₆ = 4 + 6 = 10 (Ом)
5). R₂₃₄₅₆₇ = R₂₃₄₅₆R₇/(R₂₃₄₅₆+R₇) = 100 : 20 = 5 (Ом)
6). R = R₁ + R₂₃₄₅₆₇ = 10 + 5 = 15 (Ом)
7). I = I₁ = U/R = 30 : 15 = 2 (A)
8). U₁ = I₁R₁ = 2 · 10 = 20 (B)
9). U₂₃₄₅₆₇ = I₁R₂₃₄₅₆₇ = 2 · 5 = 10 (B)
10). I₇ = U₂₃₄₅₆₇/R₇ = 10 : 10 = 1 (A)
11). I₂₃₄₅₆ = I₂ = U₂₃₄₅₆₇/R₂₃₄₅₆ = 10 : 10 = 1 (A)
12). U₂ = I₂R₂ = 1 · 4 = 4 (B)
13). U₃₄₅₆ = I₂R₃₄₅₆ = 1 · 6 = 6 (B)
14). I₆ = U₃₄₅₆/R₆ = 6 : 15 = 0,4 (A)
15). I₃₄₅ = I₃ = U₃₄₅₆/R₃₄₅ = 6 : 10 = 0,6 (A)
16). U₃ = I₃R₃ = 0,6 · 4 = 2,4 (B)
17). U₄₅ = I₃R₄₅ = 0,6 · 6 = 3,6 (B)
18). I₄ = U₄₅/R₄ = 3,6 : 10 = 0,36 (A)
19). I₅ = U₄₅/R₅ = 3,6 : 15 = 0,24 (A)
я не понял твой вопрос.