Hey!
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Solution:
Every size has 5 more blocks then the last logo.
Size 1: 7 blocks
Size 2: 12 blocks
Size 3: 17 blocks
Size 4: 22 blocks
Size 5: 27 blocks
Size 100: 407 blocks
I got 407 because for every 5 sizes its +20 so I added 20 to 7 twenty times.
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Let s equal what size
Mathematical Model: n = s + 5
Lets use size 3 as an example n = 17 + 5 (n = 22). That shows you that whatever size you use, you just add 5 to get the next size.
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Hope This Helped ;)