When eliminationing in systems of equation, how do you know when to add or subtract?

Two different linear functions are shown below with two points given from each function. use slope-intercept form or point-slope form to find the equation of each. linear function a points: (–5, –2), (–5, 7) linear function b points: (7, –5), (–2, –5) function a has: the equation of line a is: function b has: the equation of line b is:

Solve: 3x+y=6 4x-2y=18 show all work !

Solving algebraic equations 2m+3=11