A lawn is in the

Given: Cost of fencing lawn = Rs 20 per metre.

Area of lawn = 3375 m²

Length : Breadth = 5:3

Let,

Length = 5x

Breadth = 3x

We know that,

Area of lawn = Length × Breadth

⇒ 3375 m² = 5x × 3x

⇒ 3375 m² = 15x²

⇒ x² = 225 m²

⇒ x = 15 m

Therefore,

Length = 5x = 5 × 15 = 75 m

Breadth = 3x = 3 × 15 = 45 m

Now,

Perimeter of lawn = 2(length + breadth)

= 2(75 m + 45 m)

= 2 × 120 m

= 240 m

Hence,

Cost of Fencing = 240 m × Rs 20 per meter

= Rs 4800