http://session.masteringphysics.com/problemAsset/1…
Q:Consider the circuit shown in the figure . The current through the 6 ohm resistor is 4.00 A, in the direction shown.
What is the currents through the 25 ohm resistor and the 20 ohm resistor.
Help…
3 Answers

6ohms x 4A = 24V
24V/8 ohms = 3A
4A+3A=7A (current through 25 ohms)
7Ax25 ohms=175V
E=175V+24V
=199V
199V/20 ohms
=9.95A (current through 20 ohms)

Here you need to calculate the voltage across the 6 ohm resistor with V = IR. (24)
Then you will know the voltage across the 8 ohm resistor is the same. (24)
From V = IR you then calculate the current through the 8 ohm resistor.(3)
By adding the current through the 6 ohm and the 8 ohm resistors, you will have the current through the 25 ohm resistor. (7) Then from V = IR, you can calculate the voltage across the 25 ohm resistor.(175)
Now by adding the voltage across the 6 ohm and the 25 ohm resistors, you have the voltage across the 20 ohm resistor. (199)
From V = IR, you can figure the current through the 20 ohm resistor. (9.95)

v through the 6 ohm resistor=I X R=4×6=24V
v through the 8 ohm resistor=24V
I through the 8 ohm resistor=24/8=3A
total current in upper part=3+4=7A
therefore current through the 25 ohm resistor=7A
v through the 25 ohm resistor=25 x 7=175V
total voltage in the upper part=24+175=199V
therefore the voltage in the lower part=199v
I in the 20 ohm resistor= V/R=20/199=0.1A