Let the width a of the pavement be obtained from the meaning of the problem.

(48-2a)X(24-2a)=640

A=32 (truncated) or a=4

The width of the sidewalk is 4 cm.

2x？ -x=3

x？ -x/2=3/2

x？ -x/2+ 1/ 16 = 3/2+ 1/ 16 = 25/ 16

(x- 1/4)？ =( 5/4)?

x- 1/4= 5/4

x= 1/4 5/4

x 1=- 1，x2=3/2

Rectangular grassland area =5/9 X(48X24)=640.

Let the width a of the pavement be obtained from the meaning of the problem.

(48-2a)X(24-2a)=640

A=32 (truncated) or a=4

The width of the sidewalk is 4 cm.

6x？ -x- 12=0

6x？ -x= 12

x？ - 1/6x=2

x？ - 1/6x+ 1/ 144 = 289/ 144

(x- 1/ 12)？ =289/ 144

x- 1/ 12 = 17/ 12

X =17/12+12 =1.5 or x =-17/12+1/.