Hello.
Test questions, how to determine the variable.
When scores greater than the target value, skip to a frame.
When scores less than the target value, skip to another frame.
how to write the variable expression ?
thanks.

Tests scores are usually written to the variable Total... unles you specify another variable and have them written to that new variable. You have control over this.
To skip between framesyou will need to use actions. These can be added to the question objects.
Use the built in help file, there is enough information there to figure out how to do this.
You need to have an IF action followed by what you want to happen. This will involve comparing the score to a number using one of the boolean logic > < = comparitors. Then you add another action for what you want to have happen.