We have that the length of the triangle is three times its width
We'll call "x" the unknown measurement
The statement tells us that the perimeter is 104 cm, that is the sum of all its sides is equal to 104 cm
Let's remember that a rectangle has 2 pairs of equal sides, in this case, 2 sides measure 3x and two sides measure x
Therefore the sum of the 4 sides must be equal to 104 cm, we can pose the following equation
[tex]\begin{gathered} 3x+3x+x+x=104 \\ \end{gathered}[/tex]Now we clear
[tex]\begin{gathered} 8x=104 \\ x=\frac{104}{8} \\ x=13 \end{gathered}[/tex]if we are being asked the length of the rectangle and we know that the length is 3x we solve it like this
[tex]\begin{gathered} L=3x \\ L=3\cdot13 \\ L=39 \end{gathered}[/tex]The answer is that length of the rectangle is 39 cm
