A) 9 is 3². So the answer would be y = 3^2x.

B) 81 is 9². 9 is 81^-4. So the answer would be y = 81^-4.

<em>3x - y = 5</em>

**Step-by-step explanation:**

<em>2x + y = 10 | ×2</em>

<em>x - 2y = -5</em>

<em />

<em>4x + 2y = 20</em>

<em>x - 2y = -5</em>

<em>**add**</em>

<em>4x + x + 2y - 2y = 20 - 5</em>

<em>5x = 15</em>

<em>x = 15 : 5</em>

<em>x = 3</em>

<em>**replace x**</em>

<em>4(3) + 2y = 20</em>

<em>12 + 2y = 20</em>

<em>2y = 8</em>

<em>y = 8 : 2</em>

<em>y = 4</em>

3x - y =

= 3(3) - 4

= 9 - 4

= 5

**Answer:**

HL.

**Step-by-step explanation:**

Both of them are right triangles.

Sum of all interior angles = (n - 2) x 180.

Sum of all interior angles of a 70-gon = (70 - 2) x 180 = 12240°

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**Answer: 12240°**

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