Arectangular garden has length three times as great as its width. a second rectangular garden has the same width as the first garden and length that is 3 meters greater than the length of the first garden. the second garden has area of 90 square meters. what is the width of the two gardens? enter your answer in the box. m

Let x represent the width of the garden(s). Then the length of the second garden is (3x+3). The area is the product of length and width,
  90 = x(3x+3)
  30 = x(x+1)
At this point, you can recognize that 5 and 6 are factors of 30 that will satisfy this equation, or you can solve the quadratic
  x² +x -30 = 0
  (x +6)(x -5) = 0
  x = 5 . . . . . . . the negative solution does not apply

The width of the garden is 5 m.

Maybe the answer is 20mm. all i really did was just multiply, which is obvious.