+0

The age of a man 3 years ago was 11 times the age of his son. The ratio of their ages after 15 years will be 2:1

0
231
2

The age of a man 3 years ago was 11 times the age of his son. The ratio of their ages after 15 years will be 2:1

Guest Jan 24, 2015

#2
+80785
+10

The age of a man 3 years ago was 11 times the age of his son. The ratio of their ages after 15 years will be 2:1

And I assume you want to find their current ages??

Let x and y be the son's and father's ages, now...so we have

11(x-3)  = y-3 →   11x - 33 = y - 3  →   11x - 30 = y    (1)

2(x + 15) = y + 15 →  2x + 30 = y + 15 →  2x + 15 = y

And setting the "y's" equal, we have

11x - 30 = 2x + 15  rearrange

9x = 45   solve for x

x = 5, and that's the son's age now

And using (1)

11(5) - 30 = y  = 25  and that's the father's age now

CPhill  Jan 24, 2015
Sort:

#1
+18827
+10

The age of a man 3 years ago was 11 times the age of his son. The ratio of their ages after 15 years will be 2:1

$$\small{\text{ s = son and m = man }\\\\ \begin{array}{lrcllrcl} (1) & (m-3) &=& 11*(s-3) & | \quad (m-3) &=& 11s-33\\ (2) & \frac{m+15}{s+15} &=& \frac{2}{1} & | \quad m+15 &=& 2s+30\\ \hline (2)-(1):& 18 &=& -9s+63 & | :9\\ &2 &=& -s+7\\ & s&=&5 \\ \hline (1): & m-3 &=& 55-33\\ & m &=& 3+22\\ & m &=& 25 \\ \hline \end{array}$$

The age of the man is 25 and the age of his son is 5.

heureka  Jan 24, 2015
#2
+80785
+10

The age of a man 3 years ago was 11 times the age of his son. The ratio of their ages after 15 years will be 2:1

And I assume you want to find their current ages??

Let x and y be the son's and father's ages, now...so we have

11(x-3)  = y-3 →   11x - 33 = y - 3  →   11x - 30 = y    (1)

2(x + 15) = y + 15 →  2x + 30 = y + 15 →  2x + 15 = y

And setting the "y's" equal, we have

11x - 30 = 2x + 15  rearrange

9x = 45   solve for x

x = 5, and that's the son's age now

And using (1)

11(5) - 30 = y  = 25  and that's the father's age now

CPhill  Jan 24, 2015

20 Online Users

We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details