Question 1002578
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Jake is 13 years old. In 3 years his grandpa will be twice as old as Jake's dad, 
and in 7 years his grandpa will be four times older than Jake. How old is Jake's dad?
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        As printed in the post, this problem is a lame horse with three legs.

        Why ? - Because no one professional  English writer will write "will be four times older than Jake".

        Why ? - Because it is not accepted in  English to formulate  Math problems using this form.


        So, I will interpret the whole problem in THIS way

<pre> 
          Jake is 13 years old. In 3 years his grandpa will be twice as old as Jake's dad, 
          and in 7 years his grandpa will be four times as old as Jake. How old is Jake's dad?
</pre>

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;In this form, the problem is a nice arithmetic problem to solve it &nbsp;MENTALLY &nbsp;by reasoning.



<pre>
Jack is 13 years old now.

In 7 years, Jack will be 13+7 = 20 years old.

Hence, in 7 years, Jack's grandpa will be 20*4 = 80 years old.

It means that Jack's grandpa is 80-7 = 73 years old now.

In 3 years, the grandpa will be 73+3 = 76 years old.

Hence, in 3 years, Jack's father will be 76/2 = 38 years old.

It means that Jack's father is 38-3 = 35 years old now.    <U>ANSWER</U>
</pre>

Solved in this interpretation.


This problem is a good exercise, since it teaches a student to build a logical chain of steps.