Answer:
The petunia border width is 1.5 feet.
Step-by-step explanation:
Let’s define x as the border width in feet,
Given,
The garden measurements are 7 feet by 10 feet,
Thus, the dimensions of the central area without the border are (7 - 2x) feet by (10 - 2x) feet.
Therefore, the central area = (7 - 2x)(10 - 2x)
According to the problem,


( Combine like terms )
( Middle term splitting )



By applying the zero product principle,
4x - 6 or x - 7 = 0
⇒ x = 1.5 or x = 7
Since the width cannot equal the garden dimensions,
It follows that the border width would be 1.5 feet.