14 - (а - 5 2/15 ) = 3 5/12
14 - а + 5 2/15 = 3 5/12
19 2/15 - а = 3 5/12
а= 19 2/15 - 3 5/12 = 19 8/60 - 3 25/60
а= 15 43/60
проверим:
14 - ( 15 43/60 - 5 2/15 ) = 3 5/12
14 - ( 15 43/60 - 5 8/60) = 3 5/12
14 - 10 35/60 = 3 5/12
14 - 10 7/12 = 3 5/12
3 5/12 = 3 5/12