I'm going to assume that the room is a rectangle.
The area of a rectangle is A = lw, where l=length of the rectangle and w=width of the rectangle.
You're given that the length, l = (x+5)ft and the width, w = (x+4)ft. You're also told that the area, A = 600 sq. ft. Plug these values into the equation for the area of a rectangle and FOIL to multiply the two factors:

Now subtract 600 from both sides to get a quadratic equation that's equal to zero. That way you can factor the quadratic to find the roots/solutions of your equation. One of the solutions is the value of x that you would use to find the dimensions of the room:

Now you know that x could be -29 or 20. For dimensions, the value of x must give you a positive value for length and width. That means x can only be 20. Plugging x=20 into your equations for the length and width, you get:
Length = x + 5 = 20 + 5 = 25 ft.
Width = x + 4 = 20 + 4 = 24 ft.
The dimensions of your room are 25ft (length) by 24ft (width).
R = 30 because r = 1,5,10,25
30/5+1=7
6+1=7
To more easily graph this, convert it to slope-intercept form (y = mx + b, where m is the slope and b is the y-intercept):
x - y = 1
-y = -x + 1
y = x - 1
The slope is 1 and the y-intercept is -1. To graph this, plot the point (0, -1) and count 1 unit down and 1 unit to the right. Do this once more, connect the points, and you have your line.
Hope this helps.