Solving using substitution
y=4
8x-y=-12

To solve this, you need to substitute the value of Y into the equation 8X - Y = -12

So, since Y = 4, plug 4 in for Y:

8X - Y = -12
8X - (4) = -12

Now solve for X.

Does that help? Do you have any questions?

Just as a heads up this technique also works for larger equations. If Y = 3X, then you'd just plug 3X in for Y:

8X - Y = -12
8X - (3X) = -12

You got this!

Plug y=4 into equaton
8x-4=-12
add 4 to both sides
8x=-8
divide both sides by 8
x=-1

x=-1
y=4
(-1,4)

Element 17 is chlorine it is a group 7 element(halogen) and belongs to period 3 of the periodic table