Each side should increase by 2x (left & right, and up & down) so that to match the condition :
7+2x)(6+2x) = 45
Solving it will give you: 4x² + 26x - 3
For this case, the arithmetic sequence is given by:
an = 17n-1
Let's check it:
First week:
n = 1:
a1 = 17 (1) -1
a1 = 17-1
a1 = 16
Second week:
n = 2:
a2 = 17 (2) -1
a2 = 34-1
a2 = 33
Third week:
n = 3:
a3 = 17 (3) -1
a3 = 51-1
a3 = 50
Answer:
the explicit rule for the arithmetic sequence that defines the number of boxes of cereal sold in week n is:
an = 17n-1
Not sure if this is what you are looking for but welp