Question

Solve the system of equations. \begin{aligned} & -4x+7y = 20 \\\\ & y=3x+15 \end{aligned} ​ −4x+7y=20 y=3x+15 ​ x=x=x, equals y=y=y, equals

Answer 1

Answer: x = - 5

y = 0

Step-by-step explanation:

The given system of equations is expressed as

- 4x + 7y = 20 - - - - - - - - - - - -1

y = 3x + 15 - - - - - - - - - - - - - - 2

We would apply the method of substitution by substituting equation 2 into equation 1, it becomes

- 4x + 7(3x + 15) = 20

- 4x + 21x + 105 = 20

17x + 105 = 20

Subtracting 105 from the left hand side and the right hand side of the equation, it becomes

17x + 105 - 105 = 20 - 105

17x = - 85

x = - 85/17

x = - 5

Substituting x = - 5 into equation 2, it becomes

y = 3 × - 5 + 15

y = - 15 + 15

y = 0