Answer:
The average speed is 
Step-by-step explanation:
we know that
To find out the average speed divide the distance by the time
Let
s -----> average speed
d -----> the distance in feet
t ----> the time in minutes

we have


substitute
Simplify

Answer:
Step-by-step explanation:
Note how this drawing is symmetrical about a horizontal line drawn halfway between AB and CD and passing through the origin.
Line AB has been subdivided into two equal pieces of length 15, so the length of AB is twice 15, or 30. Due to the symmetry shown, line CD has the same length: 30.
Equation: 4x+15=31
I have included a picture of my work since explaining might be difficult but the way I solved this if the beginning of algebra and I hope it makes sense.
Your welcome, Katy