solve: perimenter of triangle

perimeter is 12 meters
determine values x, x+1, and x+2

x(x+1)+(x+2)=12

Don't you mean

x + (x+1)+(x+2)=12 ??

since perimeter is the sum of the sides.
3x + 3 = 12
3x=9
x=3

so the sides are 3, 4, and 5