How to calculate score in sharepoint designer 2010

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Javascript

SharePoint2010

Hi I create application quiz in sharepoint designer 2010
I still create application kuis, but i have problem :
1. every Quiz consist of QuizTitle (e.g : Fruit consist of 7 questions, Animal consists of 6 questions)
2. user will choose 1 QuizTitle (e.g : Fruit)
3. user must answer the question and the user klik button next to next question until finish
4. When user klik button next, the answer will be saved in coloumn of Mark Answer
5. user must answer the question until finish
6. when last question, i have one button finish
7. i want in button finish have 3 action :
a. when user klik button finish, automatically the last answer
will be saved in coloumn of Mark Answer
b. Then, when user klik button finish, automatically calculate
the score
c. Then, when user klik button finish, automatically direct to
other page

could you help me?
thank you