3)
The circuit is a parallel circuit. The voltage across all resistors in a parallel circuit is the same. The current across each resistor is different. Recall,
V = IR
I = V/R
From the information given,
Vt = 8
R1 = 75
R2 = 300
R3 = 2
For a parallel circuit, the formula for calculating the equivalent resistance, Rt is
Rt = 1/R1 + 1/R2 + 1/R3
By substituting the values into the formula,
Rt = 1/75 + 1/300 + 1/2
The lowest common multiple of the denominator is 300. Thus, we would multiply each term by 300 and add the results. The sum would be the numerator while the denominator would be 300. We have
(1/75 * 300 + 1/300 * 300 + 1/2 * 300)/300he
1/Rt = (4 + 1 + 150)/300 = 155/300
By taking reciprocal,
Rt/1 = 300/155
Rt = 1.94 ohms
It = Vt/Rt = 8/1.94
It = $.12