Beechtree Corporation sells chewing gum and during January they ran production machines for $22,000$ hours total and incurred $$9,500$ in maintenance costs. During July they ran production machines for $11,000$ hours total and incurred $$6,700$ in maintenance costs.

Based on this data, what is the variable maintenance cost per machine hour?

A$.$ $$2$ per machine hour

B$.$ $$0\mathrm{.}71$ per machine hour

C$.$ $$0\mathrm{.}61$ per machine hour

D$.$ $$0\mathrm{.}25$ per machine hour