Bunuel
If Ron's age is exactly twice Will's age, what is Ron's age?
(1) Five years ago, Ron's age was exactly 3 times Will's age
(2) Ten years from now, Ron's age will be exactly 1.5 times Will's age
Let R = Ron's PRESENT age
Let W = Will's PRESENT age
Target question: What is the value of R? Given: Ron's age is exactly twice Will's age We can write: R = 2W
Or we can rewrite as:
R - 2W = 0 Statement 1: Five years ago, Ron's age was exactly 3 times Will's age Ron's age 5 years ago: R - 5
Bill's age 5 years ago: W - 5
Ron's age was exactly 3 times Will's ageR - 5 = 3(W - 5)
Expand: R - 5 = 3W - 15
Rewrite as:
R - 3W = -10We now have a system of 2 equations with 2 variables:
R - 2W = 0R - 3W = -10Since we COULD solve this system,
we COULD determine the value of RSince we can answer the
target question with certainty, statement 1 is SUFFICIENT
Statement 2: Ten years from now, Ron's age will be exactly 1.5 times Will's age Ron's age in 10 years: R + 10
Bill's age in 10 years: W + 10
Ron's age will be exactly 1.5 times Will's ageR + 10 = 1.5(W + 10)
Expand: R + 10 = 1.5W + 15
Rewrite as:
R - 1.5W = 5We now have a system of 2 equations with 2 variables:
R - 2W = 0R - 1.5W = 5Since we COULD solve this system,
we COULD determine the value of RSince we can answer the
target question with certainty, statement 2 is SUFFICIENT
Answer: