Assignment: 
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Answer: 
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Explanation: 
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[ Step One ] Follow PEMDAS Order Of Operations; Calculate Within Parenthesis
Note: 

[ Step Two ] Rewrite Equation

[ Step Three ] Calculate Within Parenthesis

[ Step Four ] Rewrite Equation

[ Step Five ] Calculate Exponents

[ Step Six ] Rewrite Equation

[ Step Seven ] Multiply

[ Step Eight ] Rewrite Equation

[ Step Nine ] Subtract

[ Step Ten ] Rewrite Equation

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16 - 4 [ 3 + 2 / (9 - 7)]
16 - 4 [ 3 + 2 / 2)]
16 - 4 [ 3 + 1 ]
16 - 4 [4]
16 - 16
0 <===
That would be choice 2. One acute angle is the complement of the other
eg in a 90-60-30 triangle sine 30 = cos 60
8 ÷ 544 = 0.0147058824, 544 ÷ 8 = 68
16.8. Perimeter of a triangle is side a+ side b+ side c.