Jamal's Pet Products manufactures pet foods with healthy ingredients. Most of his competitors use a lot of filler materials and produce pet foods that are not very nutritious yet they create a sense of being full when the animals consume their products. These competitors can sell their pet foods at prices that are 20% lower than what Jamal has to charge. Jamal's sales have fallen as more competitors have entered this market. He was selling 150,000 20-pound bags of high-end dog food for $18 a bag. Now his sales have fallen to 120,000 bags. He is considering lowering his prices to $17.50 a bag but leaving his quality unchanged. He believes this price change will increase his sales by about 8,000 bags. How much are Jamal's competitors charging for a 20-pound bag of dog food?