Answer:
x = 10
Step-by-step explanation:
Use Pythagorean theorem to find the value of x
Focus only on one half of the triangle
if we slice the triangle in half, we get a right angle triangle
the base will now be 12/2 = 6
Pythagorean theorem says that 
plug 6 as a and 8 as b.
this should give you 100
now take the square root to find c (which equals x)
Ta-da!
Answer:
In order to find the slope, you need to find the difference in the x values and the difference in the y values. To do this, you write out y2-y1/x2-x1, insert your x and y values, and get your answer. Then, you find your y-intercept (where the x value is 0).
Y=5 it's a horizontal lines so b in y=mx+b would have to be 5 and since it's horizonal, it doesn't have a slope so it's just y=5
Right one unit and up ten units. Hope this helps!