How Would One Analyze a Circuit with Two Voltage Sources?
In this circuit KVL would be enough to solve. Applying KVL would sum all voltages and equal them to zero. Initially taking the given current direction as correct, we have:  5-i-9i-10-10i = 0, then i = -0.25, which tells us the current is in opposite direction regarding the one given in the image.

Found the current, Vab is the voltage across the 1ohm resitor. As current flows from B to A(we know that because we discovered its value in the topic a) ), the voltage Vab is negative, so Vab = -1*0.25 = -0.25V. 

Finally,the voltage in node B is GREATER than the voltage in node A. We know that because if you measure the voltage from B to GND you will find Vb = 5 + 0.25 = 5.25V, while Va is 5V because is the source voltage.