Answer:
44%
Explanation:
Existing garden: L*W, where L and W are the length and width (We'll assume meters, but it can be any other linear measurement, such as miles, cm, or feet, etc.).
Area, A1 = L*W
New Area, A2 = (1.2L)*(1.2W)
A2 = (1.2)*(1.2)*(L*W)
Since L*W = A1, we can write A2 = 1.44*A1
New Area = 1.44 the original area, a 44% increase.