Respuesta :

Answer: You can add 2 shells each week so you can count by 2's or multiply 2 to each week.

Step-by-step explanation:

2x1=2

2x2=4

2x3=6

2x4=8

2x5=10

2x6=12

2x7=14

2x8=16

2x9=18

2x10=20

etc..