Solution:

perimeter of rectangle = 2(l+b) units

                           here , l=50 m = 5000 cm

                                      b=50 m= 5000 cm

so,

perimeter of rectangle = 2(50+50)m

                                      =200 m = 20,000 cm

let 'n' be the number of titles

n × length of the tiles = perimeter of the rectangle

n×20 =20,000 (in cm)

[tex]n=\frac{20,000}{20}\\ \\n=\frac{2000}{2}\\ \\n=1000[/tex]

∴1000 square tiles is required to surround the garden

45,000 per 25 tiles

[tex]25 tiles = Rs 45,000\\1 box=25 tiles\\\\[/tex]

150 cm is to be tiled

so n X 20 cm = 150 cm

[tex]n=\frac{150}{20}=7.5[/tex]

∴7.5 tiles is required to tile 1.5 m or 150 cm

let 'x' be the total cost required to buy 7.5 tiles

[tex]\frac{45,000}{25}= \frac{x}{7.5}[/tex]

[tex]25x=7.5X45,000\\\\25x=3,37,500\\\\x=\frac{3,37,500}{25}[/tex]

[tex]x=\frac{3,37,500}{25}=\frac{67500}{5}=13,500[/tex]

The total cost if the perimeter of the garden to be tiled is 1.5 m is

Rs 13,500