Step-by-step explanation:
"In three years, Tonya will be 17."
14 + 3 = 17, so Tonya is 14 atm. (At The Moment)
"Tonya is twice Kevin's age." Kevin is 7, because 7 x 2 = 14.
"In another three years, Uncle Rob will be three times Tonya's age."
Since Tonya is 14, multiply 14 x 3 and you get 42.
If you're asking for the three years, 17 x 3 = 51 < Uncle Rob's age
Kevin is about 8 1/2 years old. Since 8 x 2 = 16, I multiplied 8 1/2 x 2 and got 17.
I hope this helped.