Tektonic company produces three products, lightning, plates and thunder. lightning sells for $40, plates for $80 and thunder for $60.

Variable costs per product:

Variable cost	lightning	plates	thunder
Direct materials	$12	$20	$16
Direct labour	$3	$15	$20
Other variable	$19	$25	$14

All three products use same material, Ground. The demand for product far exceeds the direct material available to produce the products. Ground costs $4 per unit and a maximum of 4,000 units are available each month. Tektonic must produce a minimum of 250 of each product. How many units of Ground will thunder use to produce the required amount to maximum its operating margin?

plz put work & calculations