Hi there!
We can solve this equation by using the systems of equations.
We can do this by subtracting like terms from both equations using substitution.
First, let's find the value of y:
6x + 3y = 21
3y = -6x + 21
y = -2x + 7
Then, we should plug it into one of the equations:
3x - 7y = 2
3x - 7(-2x + 7) = 2
3x + 14x - 49 = 2
17x = 51
x = 3
Now, we solve for y by plugging the value of x into the equation:
3x - 7y = 2
3(3) - 7y = 2
9 - 7y = 2
-7y = -7
7y = 7
y = 1
There's your answers.
Hope this helps!