algebra
posted by Theresa .
Twins Diana, and Riana are each 6 years older than their younger brother Kyle. Together, their three ages total 21 years. How old is kyle? Please show your work to help me understand how to work the problem

2T+K=32 and K=T6
Put that last into the first equation for K, then solve for T. 
2 x + x6 = 21