Wanda invites four friends to lunch. Each one orders a salad and a drink. There are two ways to compute the bill. What are they? Which property illustrated by the fact that both methods give the same result?

If the altitude is drawn to the hypotenuse of a right triangle, then the two triangles formed are similar to the original triangle and to each other. which set of triangles shows the similar triangles created by the altitude in the diagram?