Rough estimate is;
2,500 square feet should take 2 guys roughly 1 hour for 3 inches of snow
A 50 pound bag of salt should cover close to 2500 square feet.
For heavier ice adjust to about 1500 square feet with traffic,
and 1000 square feet without traffic.
So take what your paying your guys per hour and add in the cost of how many bags of salt used for your cost, double the cost and that's what you charge the client.