#30 3 ×2 ×2 ×2 5 ×2 ×2 ×2 36:12 = 3:1 3:1 3:1 1:1 3:3 3:1 9:3 4:4 = 1:1 9:1 36:12 = 3:1 21 www.it-ebooks.info