Regrind, Inc. regrinds used typewriter platens. The cost per platen is $2.20. The fixed cost to run the grinding machine is $194 per day. If the company sells the reground platens for $4.20, how many must be reground daily to break even?

So it costs 2.20 to regrind the platen and they sell them for 4.20, so they make a revenue of 2.00 per platen. In order to break even every day they need to meet the cost of running the machine which is 194. So 2.00p = 194. Thus p = 97. Hope this helps