We have to draw a square city block that has sides of 100m.
Since each unit on the grid must represent 5m, we can find how many units on the grid will represent a side of the square by dividing the 100m by 5:
The length of the square in units of the grid is 20 units.
Thus, we have to draw a square of 20 units by 20 units as shown in the following diagram: