NCERT Solutions for Class 8 Maths Chapter 2 Linear Equations in One Variable Exercise 2.6

Examples From Chapter 2 Linear Equations in One Variable

Ex. 1 If the sum of two consecutive odd natural numbers is 140. Find the bigger number.

Soln: Let the odd natural number be x.

Then,

the two consecutive odd numbers =x, x+2

Therefore,

Sum =x+x+2=140

2x=138x=69

The larger number =x+2=71.

Ex. 2 Rani has a total of Rs 300 in coins of denominations Re 1, Rs 2, and Rs 5. The number of Rs 2 coins is 3 times the number of Rs 5 coins. The total number of coins is 160. How many coins of each denomination are with Rani.

Soln: Let the number of Rs 5 coins be x
Number of Rs 2 coins = 3× Number of 5 Rs coins

 =3x
Then,

Number of Re1 coins =160−(x+3x)
=160−4x

Amount of Rs 5 coins =5x
Amount of Rs2 coins =2×3x=Rs 6x
Amount of Re1 coins =(160−4x)
=160−4x
 

As per the question, the Total amount =Rs 300
160−4x+5x+6x=300
7x=300−160
x=140/7​
x=20
 

Number of Re 1 coins =160−4x
 

=160−4×20
=80
 

Number of Rs 2 coins =3x

=3×20

=60
Number of Rs 5 coins =20