2n+5...a couple is two people so you need to multiply the number of couples, n, by 2 to get the total number of dancers. Then add the total number of organizers.
Eighty three thousand four hundred and seventy nine
Side lengths: RS=7 and ST=7, and angle=90 degrees
Why?
Since second coordinates of R and S are the same so we can just count the length by adding first coordinate of R and first coordinate of S= |-3|+4=7
Since first coordinates of R is the same as first coordinate of T so we can just count the length by adding second coordinates of S and T=5+|-2|=7
Angle: RST is =90 degrees because triangle RST is right angled triangle. Why? Because RS is parallel to X axis(the same second coordinates of R and S) and ST is parallel to Y axis(the same coordinates of S and T) .
In this example, y is equal to 8.
In order to find this, first note that the two x value expressions create a straight line. That means when we add them together they will equal 180. this will give us a value for x.
x + 10 + 10x - 61 = 180
11x - 51 = 180
11x = 231
x = 21
Now that we have the value of x, we can do the same for the straight line created by the x + 10 angle and the 18y + 5 angle.
x + 10 + 18y + 5 = 180
(21) + 10 + 18y + 5 = 180
36 + 18y = 180
18y = 144
y = 8
34 x 2 = 17 x 4
answer = 4