Chapter I : Linear Equations in two variables in two variables

Applications to practical problems:

There are some practical problems which can be sowed by reducing then to linear equations and then sowing then. Let us try to solve some of them;

Example 14. Five years ago, Neeta was trice as old as Reeta. Ten years later, Neeta will be twice as old as Reeta, How old are Neeta and Reeta now?

Solution:- Let present age of Neeta be x years and that of Reeta be y years.

5 years ago age of Neeta = x - 5

and 5 years ago age of Reeta = y - 5

10 years later age of Neeta = x + 10
10 years later age of Reeta = y + 10

Or,

Subtracting equation (1) from equation (2) we get

Putting y = 20 in equation (2) we get

x - 2 x 20 - 10 - 0

x - 50 = 0

x = 50

Age of Neeta = 50 years and age of Reeta = 20 years