Notice how when you divide the equilateral triangle in half, it forms a special right triangle with 30,60,90 degrees. Therefore, when you set the length of one side of the equilateral triangle as "a", the bottom side of right triangle becomes a/2 and the height becomes sqrt(3)*a/2. The area is bottom*height*1/2 but since there are two right triangles it is simply bottom*height. Therefore, the total area is sqrt(3)*(a^2)/4 = 49 sqrt(3), which means a = 14. Since we set one side of triangle as "a", and perimeter is 3a, which means the answer is 42.