Answer:
-4b^3 + 7b - 7
Explanation:
We have to look at terms which look like each other, for example 1b and 6b.
We can add and subtract terms which have the same degree of b.
In this question, we can safely add -1 and -6, and also b and 6b,
which gives us (-4b^3 + b - 1 ) + 6b - 6) = -4b^3 + (1+6)b +( -1 - 6) = -4b^3 + 7b - 7
The three remaining terms all have different degrees of b's (respectively 3, 1, 0), so we can't add those up any further, which tells us that this is the right answer.