The community theater in Richmond has been seeing a 10% drop in attendance every year. This year they sold 18,000 tickets.

Question is incomplete.

Assuming it means to ask, what the number of tickets they sold the previous year and the next year, the answer is:

Tickets sold last year:

x * (1 - 10%) = 18,000

x * 90% = 18,000

x = 18,000 / 90%

= 20,000 tickets last year

Next year:

= 18,000 * ( 1 - 10%)

= 18,000 * 90%

= 16,200 tickets next year.

for ex: the reciprocal of 3/4 is 4/3. it is the opposite.

reciprocal definition:

a mathematical expression or function so related to another that their product is one; the quantity obtained by dividing the number one by a given quantity.

maximum area = xy = (16)(32) = 512 ft2

to maximize the area of the garden, the side of the fence parallel to the side of the house should be 32 ft long, and the other two sides should both have length 16 ft.'

source