This problem can be solved in two ways, the long way, or the short way.
1. The long way We know that the base of the triangle is along the x-axis, and the length of the base is 20. The centre of mass is located at 2/3 of the distance from vertex (3,4) along the median, which cuts the base at (10,0). Therefore the centre of mass is located at x=3+(10-3)*2/3=23/3 y=4/3
2. The short way It turns out that the centre of mass of a triangle sheet is located at the mean of the coordinates of the three vertices, i.e. CG=((0+20+3)/3, (0+0+4)/3)=(23/3, 4/3) as before.
The answer is 4 inches. This is because the scale is 1 inch=3 feet. And when doing 12ft divided by 3ft you get 4. The 4 then represents 4 inches. Hope it helps :)
