An open shape is made up of line segments. In this type of shape there is at least one line segment that is not connected to anything at one of its endpoints, so the shape is not a closed figure. So, I am going to provide four graphs for this problem.
1. Parable
This is given by the curve:

See figure 1.
2. Cubic function.
This function is given by:

see figure 2
3. Quartic function
This curve is given by:

see figure 3
4. Cosine functionThis function is given by this equation:

See figure 4.
All these curves are open shapes. So, we can find a new open shape as the sum of all these curves as follows:

See figure 5.
The answer I came up with: 3x-18y
I think it would be 25.6 miles per hour
Steeper and the line shifted +4 up (Talking about the y intercept)
With pi, repeating decimals, etc. Hope this helped!