The perimeter of a triangle is 24 cm, one side of 5 cm 2 is 5 eighths of the perimeter. Find the length of the third side.

We find the length of the second side, since it is 5/8 of the perimeter, then you need to divide the perimeter into eight equal parts and take 5 such parts:

24: 8 * 5 = 15 (cm) – the length of the second side.
Let’s find the third side. Let her be x.

The formula for finding the perimeter of a triangle (hereinafter P):

P = a + b + c, substitute the values we know into the formula;

24 = 5 + 15 + x, solve the equation. Move 5 and 15 to the left side of the equation, in this case reversing the sign.

24 – 5 – 15 = x;

x = 4 (cm) – third party.

Answer: 4 cm.