12 feet
10 feet
15 feet
9 feet
Elora's living room

who is Elora

I don't understand

= 9 - 6n

Step-by-step explanation:

There is a common difference d between consecutive terms, that is

d = - 3 - 3 = - 9 - (- 3) = - 15 - (- 9) = - 6

This indicates the sequence is arithmetic with explicit formula

= a₁ + (n - 1)d

where a₁ is the first term and d the common difference

Here a₁ = 3 and d = - 6 , thus

= 3 - 6(n - 1) = 3 - 6n + 6 = 9 - 6n