The slope-intercept form is

If we solve for b, we have to subtract mx on each side.

Therefore, the first statement is true.
If we solve for x, first, we subtract b on each side.

Then, we divide the equation by m.

Therefore, the second statement is true.
If we solve the equation for m, first, we subtract b on each side.

Then, we divide by x.

Therefore, the third statement is false.