<human>:  Traci and Harris are baking cakes together. Traci has brought flour from her own house and Harris has 400g of flour in his house. Each cake needs 100g of flour and Traci and Harris have created 9 cakes each. How much flour, in grams, did Traci bring from her own house?
<bot>: How much flour did Traci and Harris use? ** To make the cakes, Traci and Harris used a total of 9 cakes * 100g of flour per cake = <<9*100=900>>900g of flour.
How much flour did Traci bring from her own house? ** Traci therefore brought 900g of needed flour – 400g of flour from Harris’ flour = 500g of flour from her own house.
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