How to put a returned JSON object into a variable

We have an outdoor tank with a telemetry unit that we can access via an HTML GET request. I put the GET request into NodeRED and have it outputting the JSON object as an array, but I only care about the 2 things highlighted in yellow. What is the correct way to put these 2 values into variables that can then be used elsewhere.

Have a look at to work out how to get to the parts you want - then use a change node to create a new message with the parts you want.