Tasha is planning an expansion of a square flower garden in a city park. If each side of the original garden is increased by 7 m, the new total area of the garden will be 144 m². Find the length of each side of the original garden.
Let x be the length of each side of the original garden.
The area of the original garden is x^2.
The area of the expanded garden is (x+7)^2.
We know that (x+7)^2 = 144 m².
Taking the square root of both sides, we get x+7 = 12 m.
Subtracting 7 from both sides, we get x = 5 m.
Therefore, each side of the original garden is 5 meters. Answer: \boxed{5}.