1. The problem is to solve a system of equations using the elimination method. 2. The elimination method involves adding or subtracting equations to eliminate one variable, making it easier to solve for the other. 3. Suppose the system is: $$B1: a_1x + b_1y = c_1$$ $$Rectangle: a_2x + b_2y = c_2$$ 4. Multiply one or both equations by constants so that the coefficients of $x$ or $y$ are opposites. 5. Add the equations to eliminate one variable. 6. Solve the resulting single-variable equation. 7. Substitute back to find the other variable. Since the exact equations are not provided, this is the general approach for elimination method applied to the system involving $B1$ and the rectangle equation.