Tonya is twice kevin's age. in three years, tonya will be 17. and in another three years, uncle rob will be three times tonya’s age.

T=age now of tonya
t+3=age in 3 years
t+3=17
minus 3
t=14

tonya is now 14
tonay is 2 times kevin
t=2k
14=2k
divide 2
7=k
kevin is 7

in another 3 years (3+3=6) so t+6, or 17+3, rob is 3 times tonya
20*3=60
60, that is in 6 years, so 60-6=54

kevin is 7
tonya is 14
uncle rob is 54