Question 314761
Hey,

Let's write down what we know:

p1 + p2 + p3 = 180 cm

p1 = 3*(p2)

p2 = 12 + p3

Now we can substitute:

p1 = 3*(12 + p3)  => 36 +3p3

We can then take this into the original equation to find out what the length of p3 is:

36 + 3p3 + 12 + p3 + p3 = 180

48 + 5p3 = 180

5p3 = 132 

p3 = 26.4 cm

then we put this into the other equation:

p2 = 26.4 + 12 => 38.4

and then we put these into the other equation:

p1 = 3*38.4 => 115.2

Therefore:

p1 = 115.2 cm

p2 = 38.4cm

p3 = 26.4cm

I hope this helps!