x + 3x + (2x+4) = 54 6x = = 54 - 4 = 50 x == 8 inches. The sides are x = 8 inches (shortest); 3x = 25 inches ("one side") and (2x+4) = 20 inches ("the third side"). As always, when you solve such problems, you must check at the end if the triangle inequalities are held (to check if a triangle with such sides does really exist). In this case, the triangle inequalities are valid, so such a triangle does exist.
Shortest side: x
Other side: 3x
Third side: 2x+4
perimeter: x+(3x)+(2x+4) = 6x+4
If the perimeter is 54in, then the shortest side can be found by:
6x+4 = 54
6x = 50
x = 50/6 = 25/3 ... shortest side isor about 8.333in