Learn all Concepts of Chapter 3 Class 10 (with VIDEOS). Check - Linear Equations in 2 Variables - Class 10

Last updated at May 3, 2020 by Teachoo

Learn all Concepts of Chapter 3 Class 10 (with VIDEOS). Check - Linear Equations in 2 Variables - Class 10

Transcript

Ex 3.4 ,2 Form the pair of linear equations in the following problems, and find their solutions (if they exist) by the elimination method : (iv) Meena went to a bank to withdraw Rs 2000. She asked the cashier to give her Rs 50 and Rs 100 notes only. Meena got 25 notes in all. Find how many notes of Rs 50 and Rs 100 she received. Let the number of Rs. 50 notes = x And the number of Rs. 100 notes = y It is given that total notes is 25 So, (Number of Rs 50 notes) + (Number of Rs 100 notes) = 25 x + y = 25 Also, given that Total amount withdrawn = 2000 Money withdrawn with Rs 50 note + Money withdrawn with Rs 100 notes 50 × (Number of Rs 50 notes ) + 100 × (Number of Rs 100 notes ) 50 (x) + 100 (y) = 2000 50 (x + 2y) = 2000 x + 2y = 2000/50 x + 2y = 40 Hence, our equations are x + y = 25 …(1) x + 2y = 40 …(2) We use elimination method with equation (1) & (2) − y = − 15 y = 15 Putting y = 15 in equation (1) x + y = 25 x + 15 = 25 x = 25 – 15 x = 10 So, x = 10 & y = 15 are the solution of our equations Therefore number of Rs 50 notes = x = 10 And the number of Rs 100 notes = y = 15

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Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.