Question 693144
 john is twice the age of bill. sum is greater than 21 .
 find youngest possible age of both 
:
j = 2b
:
j + b > 21
Replace j with 2b
2b + b > 21
3b > 21
b > 21/3
b > 7
:
Bill's age at least 8, then John's age at least 2(8) = 16