Which of the following properties is being used in line 2? 1. (6x + 9) + 3x

2. 6x + (9 + 3x)

3. 6x + (3x + 9)

4. (6x + 3x) + 9

5. 9x + 9

A. Distributive

B. Combine like terms

C. Associative property of addition

D. Commutative property of addition

To describe a sequence of transformations that maps triangle abc onto triangle a"b"c", a student starts with a reflection over the x-axis.how should the student complete the sequence of transformations to map triangle abc onto triangle a"b"c"? plz

Answer this two poles, ab and ed, are fixed to the ground with the of ropes ac and ec, as shown: two right triangles abc and edc have a common vertex c. angle abc and edc are right angles. ab is labeled 13 feet, ac is labeled 15 feet, ec is labeled 10 feet, and ed is labeled 4 feet.what is the approximate distance, in feet, between the two poles? 11.14 feet16.65 feet14.35 feet15.59 feet

I'm a polygon i have no parallel lines i am formed 3 line segments i have one right angle two of my angles are angles what am i