A supermarket display consists of boxes of cereal. The bottom row has 23 boxes. Each row has three fewer boxes than the row below it. The display has six rows.

Write and use a function to determine how many boxes are in the top row. Show your work.

Use the appropriate formula to determine the number of boxes in the entire display. Show your work.

The first number we start with is 23

for each row up you have three fewer boxes

An equation for this is

number of boxes = 23 - 3x

x represents the number of rows above the bottom

number of boxes = 23 - 3x=

23-3 (5) = 8

5 for the top row

bottom row has 23

1 row above 23-3 (x) = 20

2 row above 23-3 (x) = 17

3 ... 23-3 (x) = 14

4 ... 23-3 (x) = 11

5 ... 23-3 (x) = 8

therefore just add all boxes each row has

23+20+17+14+11+8 = 93