Answer:
$2,021 profit 
Step-by-step explanation:
The computation is shown below:
The Incremental Revenue from special order is 
= 4,300 units × $6.80
= $29,240
 The existed variable cost per unit is 
= $92,250 ÷ 15,000 units
= $6.15
Now the new incremental cost is 
= $6.15 + $0.18
= $6.33
 And, the total incremental cost is 
= 4,300 units × $6.33
= $27,219
 So, the yield would be 
= $29,240 - $27,219
= $2,021 profit