6.Kelly has been training to run across the country. On the first day, she ran 4 miles, the second day, she ran 12 miles, and the third day, she ran 36 miles.
a) Write an equation that models Kelly's situation?

D= d₁ + d₂ + d₃   : where D is total distance covered in the training.

Step-by-step explanation:

Let this equation model the total distance covered in the training.

Let the total distance covered in the training to be: D

Let the distance covered in 1st day be d₁ = 4 miles

Let the distance covered in 2nd day be d₂= 12 miles

Let the distance covered in 3rd day be d₃ = 36 miles

D= d₁ + d₂ + d₃

D= 4 + 12 + 36

D= 52 miles

b, 20 yards

step-by-step explanation:

the answer is b.

64

step-by-step explanation:

c=2πr=2·π·8≈64