-6b>42, -b>7, -7>b, which is the same as b<-7.
4b+6>2, 4b>-4, b>-1.
So b has to be less than -7 yet greater than -1. That's like saying the temperature is more than 7 below freezing and is higher than 1 below freezing. It can't be both, so there's no solution. On a number line showing -7 and -1, -1 is to the right of -7 (more positive than -7). But b must be to the left of -7 (more negative) and yet to the right of -1 (more positive). It can't be both!
b can't be in both the pink and blue areas.