axl169 wrote:

The sum of Doris and Fred's ages is y. 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

I have the answer by plugging in numbers, but can't figure out how this formula came about. Any help would be greatly appreciated. Thanks.

Folks, again different ways were given to answer this.

But where is our faster method i.e giving some values and then proceeding...

Let F=24 Clearly D = 36, this mean y=60

After y years ie after 60 years F= 24+60 = 84.

Go to options.........

Placing y=60 Option D gives us 84.

So it is D.........

I recommend all of u to get into these methods

Regards,

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Averages Accelerated:Guide to solve Averages Quickly(with 10 practice problems)