One morning, the temperature in a certain city was 9°c. by that evening, the temperature had dropped to -1°c. by how many degrees celsius did the temperature drop that day?

Pick the description of a geometric object that best matches the real world object box for a deck of card

Can any one me with the answers to these questions asap?

Asource of laser light sends rays ab and ac toward two opposite walls of a hall. the light rays strike the walls at points b and c, as shown below: what is the distance between the walls?