Evaluate Division
Equations are given in the format A / B = k, where A and B are variables represented as strings, and k is a real number (floating point number). Given some queries, return the answers. If the answer does not exist, return -1.0. Example Given a / b = 2.0, b / c = 3.0. queries are: a / c = ?, b / a = ?, a / e = ?