Here is another way that you should reflect on this one. There are two components to a number expressed in exponent form. Here, 5 is the BASE and -3 and 4 are the POWERS.
Step 1: Whenever the BASE is the same for two numbers expressed in exponent form (like it is here), you should ADD the powers.
Step 2: 5-3*54 = 5(-3+4) = 51
So the answer is essentially 5.