I think it's A! definitely not C or D
Answer:
7x+3y-z
Step-by-step explanation:
Starting off by separating the different variables, you should get:
(3x + 2x ) + (-z + 2z) + (3y)
Then you simplify in between the parentheses...
(5x) + (z) + (3y)
And you finally simplify the equation with only a single number of a certain variable to get your answer...
5x + z + 3y
Opposite sides being parallel proves that hte figure is a parallelogram. The sides only appear to be equal so his conclusion is not valid. He would need to show that 2 adjacent sides of the parallelogram are equal ( using the distance formula) to prove that it is a rhombus.