This is the number of combinations of 2 from 23
23C2 = 23! / 2! 21!
A quick way to do this is 23*22 / 2 = 253
Perimeter is the sum of all the sides. So we can set up an equation:

Now solve for 'x', combine like terms:
When it comes to terms with variables it's just like normal addition but we keep the variable:


So we have:

Add:

Subtract 7x to both sides:

Subtract 4 to both sides:

Divide 5 to both sides:
By using the midpoint formula and the equation of the line, the equation of the line of symmetry is x = - 2.
<h3>How to derive the equation of the axis of symmetry </h3>
In this question we know the locations of two points with the same y-value, which means that the axis of symmetry is parallel to the y-axis and that both points are equidistant. Thus, the axis of symmetry passes through the midpoint of the line segment whose ends are those points.
First, calculate the coordinates of the midpoint by the midpoint formula:
M(x, y) = 0.5 · (- 7, 11) + 0.5 · (3, 11)
M(x, y) = (- 2, 11)
Second, look for the first coordinate of the midpoint and derive the equation of the line associated with the axis of symmetry:
x = - 2
By using the midpoint formula and the equation of the line, the equation of the line of symmetry is x = - 2.
To learn more on axes of symmetry: brainly.com/question/11957987
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36 feet to metres = 10.97
first find the final velocity
vf^2 = vi^2 + 2ad
vf^2 = 0 + 2(9.81)(10.97)
vf^2 = 215.2314
vf = 14.6708
vf = vi + at
at = vf - vi
t = (vf - vi)/a
t = (14.6708)/9.81
t = 1.4955seconds