Chapter 3:Pair of Linear Equations in Two Variables

Chapter 5: Arithmetic Progression

Chapter 8: Introduction to Trigonometry

Chapter 9:Some Applications of Trigonometry

Chapter 12:Area Related to Circles

Pair of Linear Equations in Two Variables

Let the present age of Aftab be x

And his daughter be y.

Seven years ago,

Age of Aftab = x-7

Age of his daughter = y-7

According to question

x−7 = 7(y−7)

x−7 = 7y−49

x−7y = −42 ......(1)

After three years

Age of Aftab = x+3. Age of his daughter = y+3 According to the question

x+3 = 3(y+3)

x+3 = 3y+9

x−3y = 6 ....... (2)

The algebraic equation is represented by

x−7y = −42

x−3y = 6

For, x−7y = −42

or x = −42+7y

the cost of a ball be Rs y

According to the question

3x+6y = 3900

x+3y = 1300

3x+6y = 3900

And cost of 1 kg of grapes be Rs. y

According to the question,

2x+y = 160

4x+2y = 300

For, 2x+y = 160

y = 160−2x