Question 250147
I am not sure I know how to do this mathematically but your three consecutive multiples of three have to be n, n+3 and n+6
So that we have -134>3n+9<-109
33+36+39=108 too low
36+39+42=117 lowest triplet
39+42+45=126 highest triplet
42+45+48=135 too high