Community group is planning the expansion of a square flower garden in the city park if each side of the original garden is increased by 9 mm the new total area of the garden will be a hundred and sixty nine square meters find the length of each side of the original garden

4mm
The sides of the new garden can be represented by x+9. x is the original size and 9 is the added 9mm. Multiply the sides to get (x+9)(x+9) or 
this will equal the area. Create an equation to solve for the unknown original length.

Take the square root of both sides
13=x+9
Subtract both sides by 9
4=x The original side was 4mm long