Current Divider with dependent source
An easy way is to realize that both resistors are across the same voltage since their ends are directly connected.  If 70 Ohm is 5 times 14 Ohm, then the current through the smaller resistor is 5 times I.  The total current, 16A, consists of 5I + 2I + I = 8I, which means I = 16A / 8 = 2A.
Now the voltage dropped across the larger resistor is U = I times 70 Ohm = 140 V.  The power dissipation is then P = 140 V times 2 times 2A, thus 560 W.