Step-by-step explanation:

let the ratio be 3x ,4x and 5x

then, it's perimeter= 60cm

so, I know that

perimeter of a triangle= sum of its sides

then, 3x+4x+5x=60

12x =60

x=60/12

x=6

then the sides

3x=3×6=18cm

4x=4×6=24cm

5x=5×6=30cm

As I know that

area of triangle =Area = √ p ( p − a ) ( p − b ) ( p − c )

so the area of triangle

=216cm²

mark it as brainlist