WILL GIVE BRAINLIEST AND 35 POINTS Solve this system of equations.

Step-by-step explanation:

So we have the system:

To solve this, we can do some substitution. Substitute the y in the first equation for the 4x in the second:

Combine like terms:

Divide both sides by 7. The left side cancels:

So we determined that x is -3. Now, plug this number back into the second equation:

So the solution is:

Step-by-step explanation:

3x + y = -21

y = 4x

Substitue y = 4x in the first equation.

3x + 4x = -21

Combine like terms.

7x = -21

Divide both sides by 7.

x = -3

Let x = -3 for the second equation.

y = 4(-3)

Multiply.

y = -12

The solution for the system of equations is x = -3 and y = -12.

2

step-by-step explanation: