Answer: The required expression is 3x+4.
Step-by-step explanation:
Since we have given that
Let the number of wristbands that Shelly has be 'x'
Let the number of wristbands that Kaitaia has be 
Let the number of wristbands that Rea has be three more than twice the number that shelly has be

According to question, the expression that shows the number of wristbands more Katia has than Rea is given by

Hence, the required expression is 3x+4.