Question

find the value of x-y , if 3x-4y=9 and 4x-3y=12?

Answer 1

Answer:

x - y = 3

Step-by-step explanation:

3x - 4y = 9   ... (i)

4x - 3y = 12   ... (ii)

Multiplying equation (i) by 3 and (ii) by 4

9x - 12y = 27   ... (iii)

16x - 12y = 48   ... (iv)

On subtracting equations (iii) from (iv), we get

(16x - 12y) - (9x - 12y) = 48 - 27

16x - 12y - 9x + 12y = 21

7x = 21

x = 21/7

x = 3

Subtituting the value of x in equation (i)

3(3) - 4y = 9

9 - 4y = 9

4y = 9 - 9

4y = 0

y = 0

Therefore, we get that

x - y = 3 - 0

x - y = 3