1. The information given in the problem is:
- The length of a rectangular garden is 8 feet longer than the width.
- The garden is surrounded by a 4-foot sidewalk.
- The area of the sidewalk is 320 ft².
2. So, the length of the rectangular garden is:
L1=8+W1
3. The formula for calculate the area of the sidewalk, is:
A2=L2xW2
"A2" is the area of the sidewalk (A2=320 ft²).
"L2" is the length of the sidewalk.
"W2" is the widht of the sidewalk.
4. The length of the sidewalk (L2) is:
L2=L1+4+4 (4 feet on each side)
L2=L1+8
5. When you substitute L1=8+W1 into the equation L2=L1+8, you obtain:
L2=8+W1+8
L2=W1+16
6. The widht of the sidewalk is:
W2=W1+4+4
W2=W1+8
7. Now, you must substitute the length and the widht of the sidewalk into the formula A2=L2xW2:
A2=L2xW2
A2=(W1+16)(W1+8)
320=W1²+16W1+8W1+128
W1²+16W1+8W1+128-320=0
W1²+16W1+8W1-192=0
8. When you solve the quadratic equation, you obtain the value of W1:
W1=16.97 ft
9. Finally, you must substitute the value of W1 into the formula L1=8+W1:
L1=8+W1
L1=8+16.97
L1=24.97 ft
10. Therefore, the dimensions of the garden are:
L1=24.97 ft
W1=16.97 ft
