Order of Operations:

To simplify the expression follow the order of operations: (PEMDAS)

1.      Evaluate the expressions inside the Parenthesis/Brackets (P).

2.      Evaluate Powers/Exponents (E).

3.      Multiply and/or Divide in order from left to right (MD).

4.      Add and/or Subtract in order from left to right (AS). 

A simple technique for remembering the order of operations is turned

into phrase "Please Excuse My Dear Aunty Sally"

The expression is

                (Substitute y = 4 and z = 5)

First operation is evaluate the exprssion inside the parenthesis.

                      (Subtract: )

Next operation is evaluate power.

                        (Evaluate power:  )

Next operation is addition.

                              (Add: )

The value of the expression is 20.