ElectricPavlov

3 sin (pi/10  (x+5) )

3   is the amplitude     from midline the graph goes up 3   and down 3

+5    shifts the graph right ....so you can have high point at t= 0

pi/10   changes period from 2pi    to  20           2 pi / x  = 20        x = pi/10   

yes ...points are ok   first is at midline     second is at minimum

  do you understand HOW to plot the graph given the information in the Q?

Yes they are similar triangles     angle   angle   angle        all three angles in each triangle are equal

Have you tried 'b' yet? ....similar triangles

If you want to peek at what the wave should look like see here:

https://www.desmos.com/calculator/dt2d8lubmv

Short answer :   No...it is not correct.

at t= 0 it should be at it's highest point

period is supposed to be 20     you have 16

difference between highest and lowest point is supposed to be 6      yours is much more...

   also, you do not have midline resting position at y=0

try to rework it and come back......

Not sure about that answer   

I count up in my head   300    7's    

   out of  2889 digits  (see previous answer)

300/2889 =100/963

In windows     hold down the alt key and type 0176 on the numeric pad         °    there it is    

or copy it from the character map    

'x' = price of game

3/4  x     = 12   multiply both sides by    4/3

x = 12 (4/3) = .......

1-9 =9

10-99 = 90 x 2

100-999 = 900 x 3        add the red to find total digits

r speed = x

g speed = x-15

there speed of separation is the sum of these      x   +   x -15

after 7.1 hrs         (rate   x   time  = distance)

7.1  ( x      +    x-15)   = 646.1      solve for 'x'  ryan speed   then    greg speed =   x - 15