What is the current through each of the four resistors shown…

What is the current through each of the four resistors shown in the Figure 5a, if V0 = 8.0V, R1 = 68 Ω, R2 = 47 Ω, R3 = 15 Ω, and R4 = 1000 Ω. Figure 5a                 Figure 5b Keeping the resistors the same, another power supply is added as shown in Figure 5b, and now the voltages V0 = V1 = 4.0V. What is the current through each of the four resistors now?