Answer:
13,200 feet
Step-by-step explanation:
Each mile is 5280 feet, times that by 2.5, you get 13,200
y=5x+20
If you need to you can graph this in Desmos.
y is cost, 5 is price per dog, x is the number of dogs 5 and x times each other. y is total cost.
I hope this helps.
Use double angle identity

We can relate '6x' to '3x' in the same way since 6 is 2*3.

Now sub into left side of identity. Simplify until it equals right side.
Im pretty sure it is D
hope you get this right