Question

Casandra is training for a 10 mile race. On the first day of running training she runs 4 miles, each day after that she adds on 0.5 mile. On what day will Casandra run 8 miles?

Answer 1

Let the number of days needed be x.

First day = 4 miles = 3.5 + 0.5
Second day = 3.5 + 0.5(2)
Third day = 3.5 + 0.5(3)

Equation: 3.5 + 0.5x 

Find the number of days needed to run 8 miles:
3.5 + 0.5x = 8
0.5x = 4.5
x = 9
 
Answer: Casandra 8 miles on the 9th day.