An equilateral triangle an a square have the same perimeter. each side of the square measures 6cm. what is the length of each side of the triangles

Each side of the square measures 6 cm.
The square has 4 sides.
The distance all the way around the square is  (6 x 4)  =  24cm

The equilateral triangle has the same perimeter as the square.
The distance all the way around the equilateral triangle is  24 cm.
A triangle has 3 sides, and in an equilateral triangle they're all the same length.
Each side = 1/3 of 24 cm  =  8cm .

No he does not because he can only cover 12 square feet from 15 square feet which he will still need 3 more. this is because if 3×5=15 square feet and 15-12=3 which thats the answer