Answer:
rhombus
Explanation:
If ABCD is a parallelogram, then AB and CD are opposite sides and should be equal
3x - 4 = x + 18
subtract x.
2x - 4 = 18
add 4.
2x = 22
divide by 2.
x = 11
Find the lengths of the sides.
AB= 3(11)-4 = 29
BC= 2(11)+7 = 29
CD = 11+18 = 29
If BC is 29, then DA must also be 29. So all four sides are the same, it is a rhombus.