It would be (x)(x+7)=170
If you want it solved, then you would get:

=0
(x+17)(x-10)=0
And since you can't have a negative length (-17), x=10
So your side lengths would be 10 and 17 (10+7), which would give you an area of 170.
Hope that helps.
It already is in simplest form because the numerator and denonimator don't have a common factor to then divide them by.
Answer:
Slope:
y-intercept: 
Step-by-step explanation:
The equation of the line in Slope-Intercept form is:

Where "m" is the slope and "b" is the y-intercept.
The slope can be found with the following formula:

In this case you can say that:

Knowing this values you can substitute them into the formula and then evaluate, in order to find the slope. This is:

By definition, the line intersects the y-axis when the value of "x" is 0.
Notice in the table that when
, 
Therefore, the y-intercept is:

8-3x=5*2
8-3x=10
-3x=10-8
-3x=2
x=-2/3