Just divide.

0.583333. . .
^ This is the thousandths place
Look at the number after that, if it's 5 or more we round up, if it's 4 or less we round down.
It's 3, so we round down to 0.583.
The answer for both of these would be a rectangle.
A rectangular prism has 6 faces, all of which are rectangles. Slicing the prism parallel to any of the faces, whether they are end faces or bases, will result in a rectangular cross-section.
Slope=4 Point=(1,6)
Y=Mx+b
6=4(1)+b
6=4+b
-4 -4
————
2=b
Equation:4x+2