Hoyle Locking produces keys for homes and cars. As Hoyle planned for next year's production, the company decided to implement a high-low system to forecst future costs. With total production of 2.500,000 keys at a total cost of $10,000 for 2013, and total production of 3.000,000 keys at a tatal cost of $20,000 in 2014, what is the variable cost per key?