first, you need to get the variable by itself. to do that, subtract 7 from both sides. subtracting 7 from itself will cancel it out, making it 0. subtracting 7 from -5 will give you -12.
now you should have this > 6x = -12
all you need to do now is divide both by 6 to get the variable by itself. dividing 6 by 6 will cancel it out, and dividing -12 by 6 gives you -2.
so, x = -2
you can also check this by adding the x back into the problem, 6(-2)+7 still equals -5.