Changing screen elements based on value of data entry

I am trying to figure out how to do the following:

Overview:  I have a screen full of numbers but two numbers are missing (18 & 42).  The learner is supposed to look at the screen and locate the two missing numbers and type them into a data entry field on the screen.

 1. I have a data entry field on the screen - into which the learner types a number. 

2. If the number is equal to a specific answer, I want to turn the fill in the data entry field background green.  If the entered value is not equal to the answer, I want to turn the data entry field background to red.

3. If the learner chooses the incorrect number, I then want to wait a few seconds and reset the data entry field and allow them to try again until they choose the correct number.

4. There are two correct numbers - so they need to keep trying until they get both correct or the timeline runs out at 40 seconds.

If anyone can help me figure out how to do this, I would appreciate the help very much.

Edward