Question

Solve the system of equations. -4x+7y = 20 & y=3x+15

Answer 1

Substitute y = 3x + 15 to the equation -4x + 7y = 20:

-4x + 7(3x + 15) = 20          use distributive property

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

-4x + 21x + 105 = 20     subtract 105 from both sides

17x = -85     divide both sides by 17

x = -5

Substitute the value of x to the equation y = 3x + 15:

y = 3(-5) + 15

y = -15 + 15

y = 0

Answer: x = -5 and y = 0