Question

Mr Singh is 45 years old and Rahul is 9 years old. In how many years will Mr Singh's age be exactly three times Rahul's age?​

Answer 1

Step-by-step explanation:

This is an example of simultaneous equations.

The two equations we can derive from the information given is:

Let Rohit’s age = x and his brother’s = y

Then,

x+y=25 (1)

x=y+5 (2)

To isolate a variable we can do eq.(1) -eq.(2)

So,

(x+y)-x=25-(y+5)

Which simplifies to:

y=25-y-5

y=20-y

2y=20

y=10

We have found y, now we substitute y into any of the equations at the top.

For example, we use eq.(2)

x=y+5

x=(10)+5

x=15

Therefore, Rohit is 15 years old and his brother is 10 years old.

Answer 2

Answer:

in 9 years.

Step-by-step explanation:

after 9 years Rahul is 18 and mr. Singh is 54 which is 3 times of 18.

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