For this case we must algebraically rewrite the given expression. So:
x: It is the variable that represents an unknown number
"double a number" is represented as: 
"6 less than double a number" is represented as: 
So, the final expression is: 
If we want to rewrite the expression in an equivalent way, we take common factor 2:

Asnwer:

Equivalent expression: 
-x -2 I think . 3-(-5)= -2 and 2x -3x = -x
Answer:
To do this, you need to multiply out the expressions. This is a bit tedious, but remember like FOIL for binomials, for these trinomials you must multiply each term. If you need a step-by-step, I'd be happy to provide it. Let me know.
Once you have simplified the expression, you get
-x-9/2x-4
But, the problem stipulates that a must equal 1. We can equivalently factor out the negative sign and put it on the denominator with no change to write
x+9/-(2x-4) = x+9/-2x+4
So, seeing where each coefficient corresponds between the two expressions, you get a = 1, b = 9, c = –2, and d = 4.
Answer:

Step-by-step explanation:
The diagonal forms two 45-45-90 triangles, with the diagonal being the hypotenuse of both. The Pythagorean Theorem states that
, where
is the hypotenuse of the triangle, and
and
are the two legs of the triangle.
From the Isosceles Base Theorem, the two legs of a 45-45-90 triangle are always equal. Since we're given a diagonal of
, we have:

Answer: C is the correct answer Lines r and s and lines t and u must be parallel.
Step-by-step explanation: the step by step explanation is the the lines that answer C says are parallel
Lines r and s are crossed by lines t and u to form 16 angles. Clockwise from top left, at the intersection of r and t, the angles are 1, 2, 3, 4; at the intersection of s and t, 5, 6, 7, 8; at the intersection of u and s, 9, 10, 11, 12; at the intersection of u and r, 13, 14, 15, 16.