Help! Another Geometry word problem.

A leather coin purse has the shape of a triagle. Two sides are equal in length and the third side is 3 centimeters shorter than one and one-half times the length of the equal sides. The perimeter is 28.5 centimeters. Find the lengths of the sides.

Please show your work, im having so much trouble with this.

If the two equal sides are each x, then the third side is 1.5x - 3, so the perimeter is:
x + x + (1.5x - 3) = 28.5
3.5x = 28.5 + 3
3.5x = 31.5
x = 31.5 / 3.5
x = 9
1.5x - 3 = 1.5*9 - 3 = 13.5 - 3 = 10.5
So the sides are 9, 9, and 10.5

I don't understand what it means...
If two sides are equal and the third side is...????
I'm confused about the one and one half times the length of the equal sides...