Answer:
(6, 7)
Step-by-step explanation:
A rectangle means that opposite sides are parallel to each other and that opposite sides are equal in measurements.
If we look at the opposite side starting at (2, 1), we can count how long the other side should be. Counting the next point of the rectangle is (6, 1) which is a difference of 4. This means if we count from (2, 7) 4 spaces to the right, we will find our missing vertex.
(2 + 4, 7) = (6, 7)
