вычислите.
(1/13+1/14)+12/13

(1/13+1/14)+12/13 =1 1/14
1)1/13  +  1/14 =(1 × 14  +  1 × 13)/182 = 14/182  +  13/182 =  27/182
2)27/182  +  12/13  =(27 × 1  +  12 × 14)/182 = 27/182  +  168/182 =  195/182 = 15/14 = 1 1/14