Answer:
The Radar’s additional income is $123,375 and the order should be accepted. 
Step-by-step explanation:
For computing the additional income, we need to calculate the following calculations which is shown below:
1. New sales = Number of New bikes × per bike price
 = 775 × $380 
 = $294,500
2. New variable cost = Number of New bikes × per variable cost price
 = 775 × $155
 = $120,125
3. Now the contribution equals to
= Sales - variable cost
= $294,500 - $120,125
= $174,375
4. Then, the increased income is equal to
= Contribution - Fixed cost 
= $174,375 - $51,000
= 123,375
After calculation, we get to know that the incremental income is come in positive amount which is good for a company. 
And, the fixed cost remains same because it does not change with the production level
Thus, the Radar’s additional income is $123,375 and the order should be accepted.