Calculating things inside a circuit with resistors (parrallel and series)
Current division. Once you calculate current flowing through resistor 1, you need calculate how the current is split among resistor 2, 3 and 4.

They all share the same voltage drop, but not the same current.

Current Division Formula
$$ I_x = \frac{R_{total}}{R_x} * I_{In}$$

Case: Current divison among three resistors in parallel. 
$$ R_{Total} = R2 || R3 || R4 = \frac{1}{\frac{1}{R_2} + \frac{1}{R_3} + \frac{1}{R_4}} = 15$$
$$ R_x = R_2 $$
$$ I_{R2} = \frac{R_{total}}{R_2} * I_{In}$$
$$ I_{R2} = \frac{15}{50} * 2.0A$$