Hide and show multiple fields on a form based on conditions using Java Script.

The form rules don't work as there are hide and show constraints on same fields based on different number of activities. For example:

If number of activites =2 
show assesment method 1 and 2
hide assessment menthod 3 to 10 
show date 1 to 4
hide date 5 to 20
show pass fail 1to 4
hide pass fail 5 to 20

if number of activities = 3
show assessment method 1,2 and 3
hide assessment method 4 to 10
show date 1 to 6
hide date 7 to 20
show pass fail 1 to 6
hide pass fail 7 to 20. 

this creates show/hide conflicts on passfail and date fields.