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The expression is 

Commutative Property of Addition:

The order in which numbers are added does not change the sum.

For any numbers a and b,

Using Commutative Property of Addition, the statement can be written as

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Associative property of addition:

The way in which numbers are grouped when added does not change the sum.

For any numbers a, b and c;

Using Associative property of addition, the statement can be written as

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 To simplify the expression following order of operations to performed:

1.      Evaluate the expressions inside grouping symbols.

2.      Evaluate Powers

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

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

According order of operations inside the grouping symbols should be evaluated first.

First operation is adding the values within the parenthesis.

           (

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The value of the expression is 70 + z.