explain in the simplies way show caculations

Dalton Company sells slippers for $12 a pair. Variable manufacturing cost is $5.00 a pair. Typical marketing costs are $1.00 per pair. Allocated fixed manufacturing cost is $1.25 a pair So operating income per pair is $12 - $5 - $1 - $1.25 = $4.75 per Current operating level is 20,000 pairs. Maximum capacity is 23,000 pairs. Special order is 5,000 pairs at $6.25 a pair. No marketing costs are associated with the special order Q- What is the effect on operating income if we accept