Question

2x+3y=9 3x+4y=5 subsitute​​

Answer 1

$2x + 3y = 9 \: \: ... \: \: (i) \\ \\ 3x + 4y = 5 \: \: ... \: \: (ii)$

$from (i) eq. \\ \\ 2x + 3y = 9 \\ \\ 2x = 9 - 3y \\ \\ x = \frac{9 - 3y}{2} \\ \\ putting \: \: x \: \: value \: \: in \: \: equation \: \: (ii) \\ \\ 3x + 4y = 5 \\ \\ 3( \frac{ 9 - 3y}{2} ) + 4y = 5 \\ \\ \frac{27 - 9y}{2} + 4y = 5 \\ \\ \frac{27 - 9y + 8y}{2} = 5 \\ \\ 27 - y = 10 \\ \\ - y = 10 - 27 \\ \\ - y = - 17 \\ \\ y = 17. \\ \\ now \: \: putting \: \: y \: \: value \: \: in \: \: equation \: \: (i) \\ \\ 2x + 3y = 9 \\ \\ 2x + 3 \times 17 = 9 \\ \\ 2x + 51 = 9 \\ \\ 2x = 9 - 51 \\ \\ 2x = 42 \\ \\ x = \frac{42}{2} \\ \\ x = 21.$

$x = 21. \\ \\ y = 17.$

Answer 2

2x + 3y = 9 ... (i)

3x + 4y = 5 ... (ii)

from (i) eq.

2x + 3y = 9

2x = 9 - 3y

x = 9 - 3y/2

putting x value in equation (ii)

3x + 4y = 5

3( 9 - 3y/2) + 4y = 5

27 - 9y/2 + 4y = 5

27 - 9y + 8y/2 = 5

27 - y = 10

- y = 10 - 27

- y = - 17

y = 17.

now putting y value in equation (i)

2x + 3y = 9

2x + 3 × 17 = 9

2x + 51 = 9

2x = 9 - 51

2x = 42

x = 42/2

x = 21.

so , value of x = 21 and y = 17.