A 2 A current source (driving current upward) and a branch of 4 Ω in series with a 12 V source (+ at top) are both connected between a top-left node T and the bottom-left node. From T an 8 Ω resistor leads to terminal a; from the bottom-left node an 8 Ω resistor leads to terminal b; a 5 Ω resistor is connected across a–b. Find the Norton equivalent at a–b: (a) I_{N} in A and (b) R_{N} in Ω.