(Kennewick, WA)  --  Two teenaged boys are scheduled to spend a combined 20 years in prison for kidnapping an 87-year-old Kennewick, Washington woman.  The "Tri-City Herald" reports 17-year-old Dyllan K. Martin received a sentence of nine-and-a-half years after he admitted to abducting his great-grandmother.  Sixteen-year-old Billy Joseph Underwood was sentenced to ten-and-a-half years, after admitting to carrying out most of the plot to gag, bind, and kidnap the woman.  Another co-defendant, Katelyn Kenfield, was sentenced to two-and-a-half years in juvenile detention.