Financial Performance sample assessment 2 question 8 b)

Not sure if pasting a screenshot here is allowed, but the question is about a scenario of 2 different sales prices and volumes.
Whatever I try and do to calculate it, I cannot get the same answer as in part b). Answer document says £80000 but the closest I got was £64000. I think it has something to do with the fixed overheads changing based on units produced, but I just don't know, and I'm not in term time anymore so I can't reach my tutor (I missed the first chance at this exam and have it coming up this week).
If anyone can talk me though it I'll b massively grateful.
Whatever I try and do to calculate it, I cannot get the same answer as in part b). Answer document says £80000 but the closest I got was £64000. I think it has something to do with the fixed overheads changing based on units produced, but I just don't know, and I'm not in term time anymore so I can't reach my tutor (I missed the first chance at this exam and have it coming up this week).
If anyone can talk me though it I'll b massively grateful.
Comments
Therefore, you have to £240000/8000 = £30
Sales price £70
V. material cost £20
V. l. cost £10
Fixed pr per unit £30
Total cost £60
£70-£60=10x8000 units=£80000, or £70x8000-£60x8000=£80000
Demand is 10000 but company can produce only 8000 units.
Try to understand costs, how they behave when production is changing.