You need his sisters age to solve the problem. if y is the sisters age and x is Johns age, then the equation is
3y-2=x
Take the inverse cosine of 0.5162
x=59 degree
The age of Tonya is 14
The age of Kevin is 7
The age of uncle Rob is 60
Explanation:
Let T denote Tonya
Let K denote Kevin
Let R denote Uncle Rob
Tonya is twice Kevin's age, the expression can be written as
-------(1)
Kevin’s age in three years Tonya will be 17, the expression can be written as
--------(2)
In another three years uncle uncle rob will be 3 times Tonya's age, the expression can be written as
---------(3)
From (2), 
Thus, the age of Tonya is 14 years.
Substituting
in
, we get,

Thus, The age of Kevin is 7 years.
Substituting
in
, we get,

Thus, The age of uncle Rob is 60
The total number of subsets of {A, B, C} is 8. It can be found by cubing 2 and the resulting answer will definitely be 8. The correct option among all the options that are given in the question is the third option or option "c". I hope that this answer has come to your help.
Step-by-step explanation:
Scale factor
= Side length of big triangle / Side length of small triangle
= 12/5 = 24/10 = 33.6/14 = 2.4.