92:2:12+15.(78:13)-(33+54)= 92:2:12+15.(78:13)-87= 92:2:12+(15*6)-87= 92:2:12+90-87= 92:2:12+3= 92:2:15
92:2:12+15.(78:13)-(33+54)
= 92:2:12+15.(78:13)-87
= 92:2:12+(15*6)-87
= 92:2:12+90-87
= 92:2:12+3
= 92:2:15