how do you substitute y=-6x+15 and -7x-6y=-3

Question

substitute

Answer 1

y=-6x+15 and -7x-6y=-3

using substitution, take the y value of -6x+15 and substitute it into the second equation

-7x-6 (-6x+15) =-3

multiply through, combine like terms, and set x on one side of the equation

-7x +36x -90 = -3

29x = 87

x = 87/29 = 3

now substitute the found value for x back into either original equation

y=-6(3)+15

y= -18 +15 = -3

Answer 2

how do you substitute y=-6x+15 and -7x-6y=-3
substitute

1) y = -6x + 15
2) -7x - 6y = -3

Equation 1 shows the value of y in terms of x.
Substitute that value for y in equation 2.

-7x - 6y = -3
-7x - 6(-6x + 15) = -3

You have an equation with only one unknown, x.
Solve it and use that value in equation 1 to solve for y.