Solve the system by substitution.

y, equals, minus, 2, x, minus, 7
y=
−2x−7
9, x, minus, 10, y, equals, 12
9x−10y=
12

1 answer

To solve the system by substitution, we will solve one of the equations for one variable and substitute it into the other equation.

We can start with the first equation: y = -2x - 7.

We will solve this equation for y:
y = -2x - 7.

Next, we will substitute this value of y into the second equation: 9x - 10y = 12.

Substituting, we get:
9x - 10(-2x - 7) = 12.

Simplifying, we get:
9x + 20x + 70 = 12.

Combining like terms, we get:
29x + 70 = 12.

Subtracting 70 from both sides, we get:
29x = -58.

Dividing by 29, we get:
x = -2.

Now that we have the value of x, we can substitute it back into one of the original equations to solve for y. Let's use the first equation: y = -2x - 7.

Substituting x = -2, we get:
y = -2(-2) - 7,
y = 4 - 7,
y = -3.

Therefore, the solution to the system is x = -2 and y = -3.