Compound A (C7H13Br) is a tertiary bromide. On treatment with sodium ethoxide in ethanol, A is converted

Question:

Compound A (C7H13Br) is a tertiary bromide. On treatment with sodium ethoxide in ethanol, A is converted into B (C7H12). Ozonolysis of B gives C as the only product. Deduce the structures of A and B. What is the symbol for the reaction mechanism by which A is converted to B under the reaction conditions?