Question

Pat has two sheets of large, square stamps. One sheet consists of $9$ stamps arranged in a $3$-by-$3$ square. (That's $3$ stamps by $3$ stamps, not $3$ inches by $3$ inches.) The other sheet consists of $36$ stamps arranged in a $6$-by-$6$ square. The stamps on each sheet are separated by perforated creases. All the stamps on both sheets are the same shape and size.

The total length of the creases on the $3$-by-$3$ sheet is $18$ inches.

How many inches of creases does the $6$-by-$6$ sheet have?

Answer 1

Given:
3 stamps by 3 stamps. total length of crease is 18 inches
6 stamps by 6 stamps.

I illustrated the stamps and found the in the 3 stamps by 3 stamps sheet, there are 4 lines that follows the crease.

18 inches / 4 crease line = 4.50
4.50 / 3 stamps = 1.50 size of the stamps.

I also illustrated the 6 stamps by 6 stamps and found that 10 crease lines will be formed.

6 stamps * 10 lines = 60 lines
60 x 1.50 = 90 total length of the crease in the 2nd sheet.