1. The first step in solving a system of equations by the method of ________ is to obtain coefficients for x (or y) that differ only in sign.
2. Two systems of equations that have the same solution set are ________ systems.
3. A system of linear equations that has at least one solution is ________, whereas a system of linear equations that has no solution is ________.
4. In business applications, the ________ ________ (x, p) is the price p and the number of units x that satisfy both the demand and supply equations.