Answer:
356.6 mA
Step-by-step explanation:
You want to know the current flowing in the given parallel circuit when a 9 V battery is connected to its terminals.
Parallel circuit
The circuit shown has three branches connecting points A and B. The total current flowing will be the sum of the currents in those branches. The current in each branch will be ...
I = V/R . . . . . . Ohm's Law
where V is the 9 V from the battery, and R is the total resistance of the branch.
Resistors in series
The resistance in the branch containing R3 and R4 will be the sum of those resistances: 18Ω +49Ω = 67Ω.
Current
The total current will be ...
Iab = V/R1 +V/R2 +V/(R3+R4) = 9/81 +9/81 +9/67 ≈ 0.35655 . . . amperes
A milliamp is 0.001 amperes, so the current in milliamps is ...
Iab ≈ 356.6 mA
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Additional comment
Ohm's law relates the current, voltage, and resistance in a resistive circuit. Kirchoff's current law tells you the current into a circuit node is equal to the sum of the currents out of it. This is how we know the current into node A from the battery is equal to the sum of the currents out of node A through the three parallel paths.