Every year, Tabitha adds a new color to her hair.  She started this tradition when she was 15 years old, which was the year she added her second hair color.  In three years, Tabitha will have 8 different colors in the hair.  Currently, how old is Tabitha?
Since, three years from now, Tabitha will have 8 different colors in her hair, this year she has 8 - 3 = <<8-3=5>>5 colors in her hair.
Since she had 2 colors in her hair at the age of 15, she has added 5-2=3 colors since she was 15 years old.
Since she ads one color per year, 3 added colors = <<3=3>>3 added years
Thus, currently, she is 15+3=<<15+3=18>>18 years old.
#### 18