Question

Help I need help with all of my question so be aware lol

Answer 1

n = 1 corresponds to day 1
n = 2 corresponds to day 2
...etc etc...
n = 21 corresponds to day 21

Plug in n = 21
a_n = 100 + (n-1)*4
a_21 = 100+(21-1)*4 ... replace every n with 21
a_21 = 100 + 20*4
a_21 = 100+80
a_21 = 180

Answer: C) 180 yards