y = -3.5x - 3.5
y = -3.5x 3.5
I do not see a sign for the constant term (y-intercept) in the second equation.
In any case, since the equation reads y=-3.5x + (y-intercept) in both cases, the lines are parallel to each other.
If the y-intercepts are identical, then the equations are also identical, therefore there are infinitely many solutions.
If the y-intercepts are different (e.g. +3.5 and -3.5), then the two equations form distinct (i.e. not coincident) parallel lines, and therefore has solution.
So it depends on the missing sign, and you will be able to judge when the sign is given.