We need to construct the system of equations in order to solve that problem. Let's denote one-time membership fee with x and monthly fee with y. Then we can write that John paid x+6y=325 and Abigail paid x+9y=475. Solving the system of equations

, we find that x=25 and y=50. The monthly fee is 50 dollars.
the number of points a plain contains is 3
Answer: 59 + b
Step-by-step explanation: I hope this is what you mean by writing an expression
Answer:
Solve for the first variable in one of the equations, then substitute the result into the other equation.
Point Form:(7,6)
Equation Form: x=7, y=6