Question 41577
You can start by letting s = the length of the original square garden. The expanded garden will have sides of s+7 meters.
The area of the new garden is:
{{{(s+7)^2 = 144}}} Find x by taking the square root of both sides.
{{{s+7 = 12}}} Discard the negative solution as length is a positive value. Subtract 7 from both sides.
{{{s = 5}}}

The side of the original square garden is 5 meters.