Given : ABCD is a parallelogram
AB =5x-2y
DC = 4
AD = y
BC =5-x
AB = DC ( opposite sides of parallelogram are equal)
5x -2y = 4 (1)
AD = BC
y = 5-x
Putting the value of y in equation 1
5x-2y =4
5x-2(5-x) =4
5x -10+2x =4
7x = 14
x = 2
Putting the value of x in eqution 2
5-x = y
5-2 =y
3 =y