Question

Construct a word problem on simultaneous linear equation in two variables(on age,rupees,meters,speed,etc.),so,that value of one variable will be 18

Answer 1

Answer:

In the following example, the son's age x has value 18

Step-by-step explanation:

A man is three times as old as his son. Nine years ago, his son was one-fifth of his father's age. Find their present ages.

Solution:

Let son's present age = x

Let father's present age = y

ATQ, y = 3x

=> 3x - y = 0 .........(i)

Nine years ago,

Son's age = x - 9

Father's age = y - 9

ATQ,

(x - 9) = (1/5)*(y - 9)

5(x - 9) = (y - 9)

5x - 45 = y - 9

5x - y = 36 .............(ii)

Subtracting (i) from (ii), we get;

(5x - y) - (3x - y) = 36 - 0

=> 5x - 3x - y + y = 0

=>2x = 36

=> x = 18

Substituting for "x" in (i), we get:

3*18 - y = 0

=> y = 54

Son's current age = x = 18

Father's current age = y = 54

As asked, one variable has value 18