Chris and kate’s dinner bill, including a 20% tip, is $95.40. what was the amount of the bill before the tip?

So, since 95.40 is including the 20% tip, then 95.40 is 100% + 20% or 120% then.

let's say "x" is the 100% of the amount of the bill, namely the bill without the tip.

so, we know 95.40 is 120%, and "x" is 100%, then,