#### Answer

In order to solve using the elimination-by-addition method, we (1) multiply one or both of the equations by a nonzero constant so that when we add the two equations, one of the variables will cancel out. (If the variables already cancel, we can go straight to step two.) We then (2) add the two equations and (3) solve the resulting equation. Using the value of the variable found, we can then (4) solve for the other variable using either of the original two equations.