Tamil Nadu Board of Secondary EducationSSLC (English Medium) Class 9th

# 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

#### 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
Is there an error in this question or solution?

#### APPEARS IN

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