can a system of two linear equations have only two or three solutions? why or why not?

a classmate thinks that solving a system by graphing gives an exact answer when the lines appear to cross at a grid point, but only an approximate answer when they don't. explain why this isn't true.

give two systems of equations that would be easier to solve by substitution than by elimination. then give two systems that would be easier to solve with elimination. finally, explain how you decide whether to use elimination or substitution to solve a system.