SOLUTION: The age of a person is twice the sum of the ages of his two sons and five years ago his age was thrice the sum of their ages.find his present age.

Question 543176: The age of a person is twice the sum of the ages of his two sons and five years ago his age was thrice the sum of their ages.find his present age.
Found 3 solutions by lwsshak3, ajohns, JBarnum:
Answer by lwsshak3(11628)   (Show Source): You can put this solution on YOUR website!
The age of a person is twice the sum of the ages of his two sons and five years ago his age was thrice the sum of their ages.find his present age.
**
let x=present age of father
let y=sum of ages of two sons
..
At present:
x=2y
5 years ago:
x-5=3(y-10)
substitute 2y for x
2y-5=3y-30
y=25
x=2y=50
Ans:
Present age of father=25
Answer by ajohns(1)   (Show Source): You can put this solution on YOUR website!
I am new to this site and am not sure if this is the right place to make a query on the answer to question 543176.
Should the final answer not be father's present age is 50? Perhaps I am missing something.

....this is correct answer but as a tutor your obligated to explain and show all your work as giving them the answer doesnt help the student learn how to solve the next problem they come accross. ~Jbarnum
Answer by JBarnum(2146)   (Show Source): You can put this solution on YOUR website!
f=father a=first son b=second son
this says father is 2 times the age of his two sons combined.
5 years ago means you have to subtract 5 years from the father and 2 sons

this tells us both a and b are less than 25 yrs old
take this and substitute it for a in the first equation
.

b will cancel out

.
to check use the other equation
sub f and a

correct
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