Can you use the asa postulate or the aas theorem to prove the triangles congruent?

What is the y-intercept of the line given by the equation

What is the solution to this system of equations? y= 2x - 3.5 x - 2y = -14

Aclassmate 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.