The controller of Ivanhoe Industries has collected the following monthly cost data for use in analyzing the behavior of maintenance costs.

Month

Total

Maintenance Costs

Total

Machine Hours

January

$$2,730$

$350$

February

$3,030$

$400$

March

$3,630$

$550$

April

$4,530$

$640$

May

$3,230$

$550$

June

$5,330$

Determine the unit variable costs using the high$-$low method for this mixed cost. Variable cost per machine hour.