Question

HELP! ASAP! 3x - 4y = -7 and 4x + 3y = 24 solve for x and y

Answer 1

`\boxed{x = 3 \: and \: y = 4}`

Explanation:

`3x - 4y = -7.....(eq)1 \\ 4x + 3y = 24 .....(eq)2 \\ \boxed{step \: 1}\\ * 4....3x - 4y = -7 \\ * 3....4x + 3y = 24 \\\boxed{step \: 2} \\ 12x - 16y = - 28 \\ 12x + 9y = 72 \\ \boxed{step \: 3} \\ 12x - 12x - 16y - ( + 9y) = - 28 - 72 \\ - 25y = - 100 \\ y = ( - 100)/( - 25) \\\boxed{ y = 4}\\.................. \\ \boxed{step \: 4} \\ substitute \: the \: value \: of \: y \: in \: .....(eq)1 \\ 3x - 4y = -7 \\ 3x - 4(4) = - 7 \\ 3x - 16 = - 7 \\ 3x = - 7 + 16 \\ 3x = 9 \\ x = (9)/(3) \\ \boxed{ x = 3}`

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Answer 2

x = 3

y = 4

Explanation:

3x -4y = -7

4x + 3y = 24

write the first equation in terms of y

3x - 4y = -7

3x + 7 = 4y

3x/4 + 7/4 = y

now substitute that into the second equation

4x + 3y = 24

4x + 3(3x/4 + 7/4) = 24

4x + 2.25x + 5.25 = 24

6.25x + 5.25 = 24

6.25x = 24 - 5.25

6.25x = 18.75

x = 18.75/6.25

x = 3

last step, substitute x for 3 in the equation.

y = 3x/4 + 7/4

y = 3*3/4 + 7/4

y = 9/4 + 7/4

y = 4