7. x =3 because the other side is 3

and y = 5 because the other side is 10 and 2y when y is 5 is 2*5 which is 10.

8. remember the rules of a parallelogram,the opposite angles and sides are equal, if not, it wont be a parallelogram , so if CD is 6, then AB is also 6, bear in mind that AD is not 6 and BC is not 6 but AD is the same as BC.

9. the total angles in any 4 side shape is 360 degrees, so add the angles which is 137+137+a(we dont know) +b(we dont know) MUST EQUAL 360

remember that a is the same as b so we have

274 + a +a=360

274+2a=360

2a=360-274

2a=86

a=43

so that is the size of the angle

hope that helps