Please help me 12 points

The multiplication property of zero states that the product of any number and 0 is 0. what must be true about either a or b to make ab=0

Determine whether the quadrilateral below is a parallelogram. justify/explain your answer (this means back it up! give specific information that supports your decision. writing just "yes" or "no" will result in no credit.)

How many $20 bills do you need to have to make $280