Yes it is possible. Some rectangles are also a rhombus. In this case, we'd have a square. A rectangle has all four angles congruent (to 90 degrees each). A rhombus has all four sides congruent. A square fits the description of having all four angles congruent and all four sides congruent.
The slope of the line whose equation follows the point-slope form (y=mx + b) is m. Transforming the equation 5y = x - 3 into the point-slope form by dividing the whole equation by 5 results to . The slope, m, is 1/5.