Answer:
2.4 yd
Explanation:
Let the width of the walkway = x.
total length = x + 7.5
total width = x + 4.5
total area = (x + 7.5)(x + 4.5)
total area = 68.31 yd²
(x + 7.5)(x + 4.5) = 68.31
x² + 4.5x + 7.5x + 33.75 - 68.31 = 0
x² + 12x - 34.56 = 0
x = [-12 ± √(12² - 4(1)(-34.56)]/(2 × 1)
x = [-12 ± √(144 + 138.24)]/(2 × 1)
x = [-12 ± 16.8]/2
x = 2.4 or x = -14.4
Answer: 2.4 yd