The initial amount is 2. To find next week's amount, we divide this week's amount by 3. Find a formula that gives the amount A after t weeks.

The Formula is:    Aτ = Aτ-₁ / 3

Step-by-step explanation:

Initial Amount (in Week 1) = 2

Next Amount (in Week 2) = 2/3

Amount in Week 3 = 2/3 ÷ 3  = 2/3 × 1/3  = 2/9

Amount in Week 4 = 2/9 ÷ 3  = 2/9 × 1/3  = 2/27

You're to find a formula that gives the amount after a number of weeks; where

Amount = A and     Weeks or Time in Weeks = t

A formula implies a general means of solving for the amount in any given week.

That formula is derived thus:

A₁ = 2     A₂ = 2/3     A₃ = A₂/3     A₄ = A₃/3

Summarizing,

Let t = the subscripts of the A's, hence t = time in weeks

The Formula is:    Aτ = Aτ-₁ / 3

where τ is a Greek letter used to represent English letter t

The subscript t-1 represents the period or week before the desired or current period

Asubscriptt-1 represents the amount in that previous week. So to get the amount in the current or desired week, simply divide this figure by 3.

KUDOS.

care to share were the trapezoid shown is ?