That would be B) 25% off. Hope this helps!
Answer: 
<u>Move all terms to the left</u>
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<u>Add all the numbers together, and all the variables</u>
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<u>Multiply elements</u>
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<u>Move all terms containing d to the left, all other terms to the right</u>
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Answer:
The area of the triangle is of 21 units of area.
Step-by-step explanation:
The area of a triangle with three vertices
is given by the determinant of the following matrix:

In this question:
Vertices (3,0) (9,0) (7,6). So




The area of the triangle is of 21 units of area.