Tamil Nadu Board of Secondary EducationSSLC (English Medium) Class 9th
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Solve, using the method of substitution 10% of x + 20% of y = 24, 3x – y = 20 - Mathematics

Sum

Solve, using the method of substitution

10% of x + 20% of y = 24, 3x – y = 20

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Solution

`10/100 xx x + 20/100 xx y` = 24

`x/10 + y/5` = 24

Multiply by 10

x + 2y = 240 → (1)

3x – y = 20

– y = 20 – 3x

y = 3x – 20 → (2)

Substitute the value of y in (1)

x + 2(3x – 20) = 240

x + 6x – 40 = 240

7x – 40 = 240

7x = 240 + 40

7x = 280

x = `280/7`

x = 40

Substitute the value of x = 40 in (2)

y = 3(40) – 20 = 120 – 20

y = 100

∴ The value of x = 40 and y = 100

Concept: Methods of Solving Simultaneous Linear Equations by Substitution
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APPEARS IN

Samacheer Kalvi Mathematics Class 9th Tamil Nadu State Board
Chapter 3 Algebra
Exercise 3.11 | Q 1. (iii) | Page 126
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