Final answer:
To factor the expression completely, you can factor out the common term 'b' from each term: 3bx, -4ay, and 4by. The factored form is b(3x - 4a + 4y).
Step-by-step explanation:
To factor completely, we can look for common terms in the three expressions: 3bx, -4ay, and 4by.
The common term is 'b', so we can factor out 'b' from each term:
3bx - 4ay + 4by = b(3x - 4a + 4y)
The completely factored form of the expression is b(3x - 4a + 4y).