Answer: Susie walked 4000 kilometers on day 18 of her program
Explanation:
The question explains an arithmetic progression of Susie's walk program
Now the nth term of an AP is given as
an = a1 + (n - 1 ) d
a1 =First term = 600 m
common difference , d =200
The 18th day of her program will be
a18 = 600+ (18 - 1 ) 200
a18 = 600+ 17 x200
a18 = 600+3,400
a18 = 4000