Since you're working with the ASA postulate, you're looking to show congruence of the angles at either end of a side. You're given side AC and angle A as congruent with their counterparts. Obviously, you also need to show congruence of angle C with its counterpart, angle Z.
selection B is appropriate
The slope formula is y=mx+b. Y is a variable. m is the actual slope. It tells you how much the x will move. For example, if a slope was 2x, x would move up 2 and over 1. If the slope was 1/2 x, x would move up 1 and over 2. A way to remember slope is rise over run. X is a variable. B is a point on the y-intercept that is will the line will start. An example is y=x+3. The y-intercept is 3 and x would move up one and over one.
Triangle area formula 1/2bxh
12/2=6 6x12=72