b) (36 supra 13 ÷ 4) ÷ (5 supra 26 ÷ 7 supra 36) si c)

(36/13:4):(5/26÷7/36)=
=(36/13×1/4):(5/26×36/7)
=18/52 : 180/182
=9/26 : 90/91
=9/26×91/90
=819/2340