We are given xy = wz. Dividing both sides of the equation by de, which is nonzero, we obtain xy/de = wz/de. Multiplying both sides by e/w gives exy/wde = z/d. Since x/d = w/e, z/d = dxy/xde = y/e, and we are done.
Fact 4: In this step, we are asked to show that a and b are relatively prime, and that a > b.
We already know x/d = a and z/d = b. Since x > z, x/d > z/d as d > 0. Therefore a > b. We also have: