A tessellation has 2 pairs of congruent angles around the point of interscetion. The measure of each of one point of congruent angles is 40 degress. What is the measure of each one of the pair of congruent angles.

This is all you, but i can give you some topics that you could try. if it rained when you want to do something outdoors, it 'limits' that human activity. maybe you want to do an experiment that goes throughout the whole year and you have to have above freezing the entire year. this 'limits' your activity. i thought of those just off of the top of my head. something that gets to me that might be getting to you is you are thinking too hard about what to do. think simply, and if it is too simple, then bump it up just a little bit.

Ba rock that formed 1,400 million years ago!

Well, a and b together would be negative. b alone would also be negative.