Răspuns: 31/36
( 2 5/18 - 1 5/12) = ?
(2 x 18 + 5 ) / 18 - ( 1 x 12 + 5 ) / 12 = (36 + 5 ) / 18 - 17/ 12 = 41/18 - 17 / 12 - amplificare la prima fractie cu 12 iar la a doua fractie cu 18 => 492 / 216 - 306/216 = (492 - 306 ) / 216 = 186/216 = 62/72 = 31/36
