Question 405396
Let Karen be "k", Greg be "2k-15", and Olivia be "k+10". 
You know that together, their weights are *at least* 460 pounds. This means that you'll be using a ≥ sign, for greater than or equal to. 
Having your variables in place--you choose the person whose weight is used as a reference point most of the time--just plug them into your equation.
You know that they're 460 pounds altogether, so just add up. 
k+2k-15+k+10≥460
Since you just need an equation, you don't have to simplify fully. 
Hope this helps :)