Mary is about as many days as John in weeks, and Mary is as many months as Robert in years. Mary, John and Robert together are 144 years. Can you tell me Robert’s age in years?	Choose the correct answer.
A) 60 years
B) 86 years
C) 108 years
D) 96 years
E) 84 years
Let r be Robert’s age in years. If j is John’s age in years, then John is 52j weeks old. If m is Mary’s age in years, them Mary is 365m days old. Thus,
365m = 52j
Since Mary is 12m months old,
12m = r
Since Mary, John and Robert together are 144 years,
m + j + r = 144,
The above system of 3 equations in 3 unknowns (m, j and r) can be solved as follows:
r/12 + 365r/(52 x 12) + r = 144 or
52r + 365r + 624r = 624 x 144 or
r = 624 x 144/1041 = 86 years
Answer: 86 years
<result>B</result>
Mary is about as many days as John in weeks, and Mary is as many months as Robert in years. Mary, John and Robert together are 144 years. Can you tell me Robert’s age in years?