Question

find x and y so that abcd is a parallelogram AB= 3x+2y BC=3 CD=7 DA= 2x+y

Answer 1

In a parallelogram, opposite sides are congruent.
Then AB = CD and BC = DA
3x + 2y = 7
2x + y = 3
Multiply the second equation by -2 and add to equation 1:
3x + 2y = 7
-4x - 2y = - 6
--------------(add)
-x = 1
x = -1
Now substitute x = -1 in first original equation:
3x + 2y = 7
3(-1) + 2y = 7
-3 + 2y = 7
2y = 10
y = 5