CBSE Notes, Lectures

CBSE - Mathematics - Pair of Linear Equations in Two Variables

Pair of Linear Equations in Two Variables

NCERT Exercise Exercise 3.4

2. Form the pair of linear equations in the following problems, and find their solutions (if they exist) by the elimination method:

(ii) Five years ago, Nuri was thrice as old as Sonu. Ten years later, Nuri will be twice as old as Sonu. How old are Nuri and Sonu?

(ii) Let present age of Nuri = x
and present age of Sonu = y
According to the given information,question,(x - 5) = 3(y - 5)
x - 3y = -10 ... (i)
(x + 10y) = 2(y + 10)
x - 2y = 10 ... (ii)
Subtracting equation (i) from equation (ii), we get
y = 20 ... (iii)
Putting this value in equation (i), we get
x - 60 = -10
= 50
Hence, age of Nuri = 50 years and age of Sonu = 20 years

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