BTGmoderatorDC wrote:The sum of the ages of Doris and Fred is y years. If Doris is 12 years older than Fred , how many years old will Fred be y years from now, in terms of y ?
(A) y - 6
(B) 2y - 6
(C) y/2 - 6
(D) 3y/2 - 6
(E) 5y/2 - 6
Let F = Fred's PRESENT age
Doris is 12 years older than Fred.
In other words, Doris' age = F + 12.
So, the sum of their ages = F + (F + 12)
Simplify to get: sum of their ages = 2F + 12
The sum of the ages = y
2F + 12 = y
Now solve for Fred's age (F).
Start with: 2F + 12 = y
Subtract 12 form both sides: 2F = y - 12
Divide both sides by 2 to get: F = (y - 12)/2
Rewrite as: F = y/2 - 12/2
Simplify: F =
y/2 - 6
So, Fred's PRESENT age is
y/2 - 6
How many years old will Fred be y years from now, in terms of y?
Add y to Frank's PRESENT age to get:
y/2 - 6 +
y
Check the answer choices . . .
y/2 - 6 +
y isn't there!
Looks like we need to SIMPLIFY
y/2 - 6 +
y =
y/2 - 6 +
2y/2 (get common denominator of 2)
= 3y/2 - 6
= D
Cheers,
Brent
