Problem 12-58 Resistor network

In the Figure, what is the
(a) current through the $150 \Omega$ resistor?
(b) potential difference across the $250 \Omega$ resistor?
(c) current through the $350\Omega$ resistor?
(d) potential at $\text{point A}$ (assuming zero potential at the negative terminal of the battery)

[Ans. (a) $0.057 \;A$   (b) $14 \;V$   (c) $0.035\; A$  (d) $21 \;V$ ]

The object in questions like this is to determine the current provided by the battery. To do this we need to reduce the circuit to its simplest form, i.e. a single resistance $R$ across the battery of voltage $V.$
 
Which resistors should be combined first?

(A)  $150\Omega$ and $350\Omega$

(B)  $550\Omega$ and $250\Omega$

(C)  $350\Omega$ and $550\Omega$