I truly need help with these calculations. I need to know how to get the calculations and exactly what information to use and where. I'm just hitting a brick wall here. Thank you

Gevorg's Electronics manufactures TVs and DVDRs. During April, the following activities occurred: Required: Compute the following variances in terms of the contribution margin. Determine the total sales-mix variance. Determine the total sales-quantity variance. Determine the total sales-volume variance