Call x the length of one of the two equal sides

Call y the length of the third side

2x+y=32

because perimeter = length of all three sides added together

2x=y+8

because "2 sides of equal length are together 8cm longer than third side"

One way to solve is by substitution

y=2x-8

so,

2x+(2x-8)= 32

4x=40

x=10

So each of the equal sides has length ten

You can probably take it from here