Question

Bhanu’s father is 4 times as old as Bhanu. After 5 years, he will be 3 times as old as his son. Find their present ages.

Answer 1

Hint: These are very general and easy problems. Just assume some variables according to your need. Then just apply some basic algebraic formulas. But always keep in mind that these are real life problems. So, a son's age is always less than his parents’ and practical.

Complete step-by-step answer:
Let us assume that,
Bhanu’s age is \[x\]
And, age of Bhanu’s Father is \[y\]
At present Bhanu’s father is 4 times as old as Bhanu. ……….[ it is given]
So, we can say that……..\[y\]= 4\[x\]
Now, following the second instruction
After 5 years the age of Bhanu will be \[x+5\].
And the age of Bhanu’s father will be \[y+5\].
It is said that after 5 years, Bhanu’s father will be 3 times as old as his son.
So, we can say that
\[y+5=3\left( x+5 \right)\]
  Or, \[4x+5=3x+15\]…………..[Here, we are putting the \[y=4x\]]
  Or, \[x=15-5\]
   Or, \[x=10\]
 So, at present Bhanu’s age is 10 years.
Now, age of Bhanu’s father is \[4x\] = 4 X 10 = 40 years.
Hence,
 Bhanu’s present age is 10 years.
 Bhanu’s father’s age is 40 years.

Note: In such types of problems you can also assume any number as an age according to your comfort in spite of assuming x and y. Then just follow the steps with your assumed number and you can also get the same result . But still variables are assumed for simplicity.