What is the rule to. it is a two part sich as double it and subtract

In the diagram of circle o, what is the measure of zabc?

Matt had 5 library books. he checked out 1 additional book every week without retuening any books. whats the matching equation

Maci and i are making a small kite. two sides are 10". two sides are 5". the shorter diagonal is 6". round all your answers to the nearest tenth. 1. what is the distance from the peak of the kite to the intersection of the diagonals? 2. what is the distance from intersection of the diagonals to the top of the tail? 3. what is the length of the longer diagonal?