Giving reasons for your answer based on the type of system being developed, suggest the most appropriate generic software process model that might be used as a basis for managing the development of the following systems: A university accounting system that replaces an existing system An interactive travel planning system that helps users plan journeys with the lowest environmental impact.

For the university accounting system that replaces an existing system the appropriate generic software process model is Waterfall model

This is because the requirement of the system can be predicted in advance because of the existing system and secondly, this a mission critical system and the requirement are stable and reusable

For the  interactive travel planning system that helps users plan journeys with the lowest environmental impact the appropriate generic software process model is Prototype Model

This is because the user's requirement may likely change and fast delivery is essential to be implemented and for this the prototype model can save time of development to focus on essential functions first.

Explanation:

In order to get a better understanding of the answers above let define the concept of

Waterfall Model:

   We can define waterfall model as a type of software development approach that explains step by step development method, this software development approach consist of five to seven steps and each step is characterized by different tasks and objectives and these steps combined together explains the the life cycle of the the software development process.

Prototype Model

   We can define prototype model as a type of system development approach whereby an estimation(i.e the prototype) of the final system is constructed,tested and adjusted until the desired result is obtained and the the main system is then constructed with the specification of the perfect estimation or prototype for example when constructing a bridge the engineer apply this methodology by first constructing an estimation or prototype of what the bridge should look like and then various test and adjustments are  been carried out on this prototype bridge afterward he main bridge is been constructed with the specification of the prototype.  

the major difference between the two is the objective and the reward of the game. candy crush has a puzzle theme with the objective of meeting a specific quota of points or objects, you are able to gain access to the next level and compete with peers on the process. on duolingo the objective is rather different, you are given sets of questions for you to answer for you to move to the next level and as for the reward, you are able to learn available language as this is an app developed to teach the user about other languages.