Answer:
Variable cost per unit= $7.2 per unit
Step-by-step explanation:
Giving the following information:
Month Total Maintenance Costs Total Machine Hours 
January: $2,590 - 330 
February: $2,890 - 380 
March: $3,490 - 530 
April: $4,390 - 660 
May: $3,090 - 530 
June: $5,470 - 730
To calculate the variable cost under the high-low method, we need to use the following formula:
Variable cost per unit= (Highest activity cost - Lowest activity cost)/ (Highest activity units - Lowest activity units)
Variable cost per unit= (5,470 - 2,590) / (730 - 330)
Variable cost per unit= $7.2 per unit