The area formula for a triangle is:
(b * h)/2
It could also be written as:
h * (b/2).
So basically,
(x + 3) * ((2x - 6)/2)
And then you could say:
(x + 3) * (x - 3)
Then just multiply each individual number by eachother.
x * x + x * -3 + 3 * x + 3 * -3
Or,
[tex] x^{2} [/tex] + -3x + 3x - 9
-3x + 3x is equal to 0.
So therefore:
[tex] x^{2} [/tex] - 9 is your final answer.