Marika is training for a track race She starts by sprinting 100 yards. She gradually increases her distance, adding 4 yards a day for 21 days how far does she sprint on day 21

using an=100 + (n-1) 4

For this case, you must use the given expression, taking into account that:

n = number of days.

We have then that for day 21, n = 21.

Substituting we have:

a21 = 100 + (21-1) * 4

a21 = 180

Answer:

she sprints 180 yards on day 21