Ammeter connected between 2 parallel branches (Isaac)

I have looked through the other threads on this question, But still don't understand how to get to the answer. https://isaacphysics.org/questions/current_between_resistors_sym?board=b9811b63-e09f-44ea-94fb-071c67fe87cf&stage=a_level

The approach I have been trying to use is this: https://imgur.com/t71uluZ, (image from another thread) however my difficulty is still working out the total resistance of the circuit which i need to multiply by 1/6. Could anyone explain how to do find the total resistance / if there is a better approach? I've been struggling for a while now

(edited 2 months ago)

I have looked through the other threads on this question, But still don't understand how to get to the answer. https://isaacphysics.org/questions/current_between_resistors_sym?board=b9811b63-e09f-44ea-94fb-071c67fe87cf&stage=a_level

The approach I have been trying to use is this: https://imgur.com/t71uluZ, (image from another thread) however my difficulty is still working out the total resistance of the circuit which i need to multiply by 1/6. Could anyone explain how to do find the total resistance / if there is a better approach? I've been struggling for a while now