I'm not exactly sure of what you mean, but I think you need to find the value ofywhen x is 0.7547.

The point of this is to substitute (plug in) 0.7547 for x:

When youyou get:put 0.7545 into the equation

I think that concept is what you didn't understand. Do you see what it means to "put a number into an equation?" You have to substitute that number for the variable (e.g. x).