2x + y + z = 12
10.00 5x + 5y + 5z = 20
x - 4y + z = -21

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.)

Compare the cost of the bike trips from the two companies shown.for both the cost in a linear function of the number of days which statements is true

Simplify (8x2 − 1 + 2x3) − (7x3 − 3x2 + 1). −5x3 + 11x2 − 2 5x3 − 11x2 + 2 x3 + 2x2 + x3 x3 − 2x2 − x3