Help ASAP! I don’t understand.

Me! 50 points! why does when we come home, our door is unlocked and there is grease on the door knob, me solve this , and i don't know what category this goes under

What is the expression in factored form? 3x^2 + 18x + 24 a. 3(x+2)(x+4) b. 3(x-2)(x+4) c. 3(x-2)(x-4) d. 3(x+2)(x-4)

Satchi found a used bookstore that sells pre-owned dvds and cds. dvds cost $9 each, and cds cost $7 each. satchi can spend no more than $45.