Determine whether the lines given by the equations below are parallel, perpendicular, or neither. Also, find a rigorous algebraic solution for each problem. a. {3y+4x=12 \brace -6y=8x+1} b. {3y+x=12 \brace -y=8x+1} c. {4x-7y=10 \brace 7x+4y=1}