###Human: Tilly needs to sell 100 bags at $10 per bag to make $300 in profit. How much did she buy each bag for?, ### Assistant: Tilly will make 100 x $10 = $1000 in total
She has spent $1000 - $300 = $700 on 100 bags
Each bag cost Tilly $700 / 100 = $7 
 So the answer is :  7