To get #%# of change, you use #c/o = x/100#, where #c# stands for the change between each number, and #o# stands for the original number. #x# is the percent you are trying to find, and is represented over #100# since percent is the ratio of #100#.

So, the first step is to subtract each number from each other. #15.6 - 11.4 = 4.2#. #4.2# is our #c# value wince it is the change between each number. And of course, #o = 15.6# since that is the original value.

Now you can set up your equation. #4.2/15.6 = x/100#. Through cross multiplication, you can say that #15.6x = 420#.

Your last step, of course is to solve for #x#. Divide each side by #15.6#, and that is your percent. #x = 26.92%#