A company developed the following per-unit standards for its product: 2 gallons of direct materials at $8 per gallon. Last month, 3,000 gallons of direct materials were purchased for $22,800. The direct materials price variance for last month was

a. $22,800 favorable

b. $600 favorable

c. $1,200 favorable

d. $1,200 unfavorable

How do I solve this?

Thank you