Since each grid square represents 30 meters, it will take 3 grid squares to represent 90 meters. The scale drawing will be a square 3 grid squares on a side.
The slope of a line is y2 - y1 / x2 - x1 The origin is (0,0) That means the slope is 0--5/0--4 That becomes 5/4 This can also be expressed as 1 1/4, or 1.25