Answer:
currently (before the increase in raw materials), the cost of producing 1 unit = [(2 x $10) + (5 x $4) + (8 x $3)] / 640 = $64 / 640 = $0.10 per unit
if raw materials increase to $8, then production costs per unit = [(2 x $10) + (5 x $8) + (8 x $3)] / 640 = $84 / 640 = $0.13125 per unit
per unit costs will increase by ($0.13125 - $0.10) / $0.10 = 31.25%
when the price of inputs increase (e.g. raw materials), the aggregate supply curve shifts to the left, resulting in higher prices, lower total output and eventually higher unemployment.