To solve this problem, first subtract #color(red)(8.3)# from each side of the equation to isolate the #c# term while keeping the equation balanced:

#c/5.3 + 8.3 - color(red)(8.3) = 11.3 - color(red)(8.3)#

#c/5.3 + 0 = 3#

#c/5.3 = 3#

Now, multiply each side of the equation by #color(red)(5.3)# to solve for #c# while keeping the equation balanced:

#c/5.3 xx color(red)(5.3) = 3 xx color(red)(5.3)#

#c/color(red)(cancel(color(black)(5.3))) xx cancel(color(red)(5.3)) = 15.9#

#c = 15.9#

To validate this solution, substitute #15.9# for #c# in the original equation and ensure the left side of the equation calculates out to #11.3#

#15.9/5.3 + 8.3 = 11.3#

#3 + 8.3 = 11.3#

#11.3 = 11.3#