3:1 long run. That's 75 minutes at RPE 2-3, 15 minutes finish at RPE 5.
If you haven't experimented with gels and drinks, start here. Take a bottle to sip from every 20mins or so. Consume 1 gel at the 50 minute point. Try using sports drinks for hydration and note any stomach problems after the gel. If so, switch to water in future runs.
3 x 400 even split for each at RPE 2-3