You'll want to use either an aggregator or a statisticsCalculator. In either case you'll want to set the group-by parameter to CAD LAYER.
Hi,
I would agree with @jdh's answer. If you are a relative new comer to FME then I think that the StatisticsCalculator is probably an easier transformer to get to grips with and understand.
If you want to use the StatisticsCalculator then you might want to consider the following parameters:

Setting the Group By to "CAD LAYER" and "Area (Divider)" will ensure that if the features have the same "CAD LAYER" and "Area (Divider)" values then the "Area (m2)" will be summed and counted appropriately. If you just Group By "CAD LAYER" then a feature with Area 1, Layer 1 would be grouped with a feature with Area 2, Layer 1 which you might not necessarily want.
Hi,
I would agree with @jdh's answer. If you are a relative new comer to FME then I think that the StatisticsCalculator is probably an easier transformer to get to grips with and understand.
If you want to use the StatisticsCalculator then you might want to consider the following parameters:

Setting the Group By to "CAD LAYER" and "Area (Divider)" will ensure that if the features have the same "CAD LAYER" and "Area (Divider)" values then the "Area (m2)" will be summed and counted appropriately. If you just Group By "CAD LAYER" then a feature with Area 1, Layer 1 would be grouped with a feature with Area 2, Layer 1 which you might not necessarily want.
Thanks sipsysigh, StatisticsCalculator did the job!