Equivalent Resistance in a short circuit

Find the equivalent resistance across terminals a and c. I don't know how the current flows in this circuit so I can't find the equivalent resistance.

Answer

What if you rearranged the elements like this?

^{simulate this circuit – Schematic created using CircuitLab}

Then it's pretty simple to see the equivalent resistance is 6R/3 + R = 3R

Step one if you're stuck on a problem like this is to redraw it.