9. X=9
because this shape is a Parallel quadrilateral, where both pairs of opposite sides are parallel. And also, Opposite sides are congruent.
So 10= 2x - 8
18= 2x
x=9
10. x= 12
This is a Isosceles triangle, which is a triangle that has two sides of equal length.
Based on the Isosceles Triangle Theorem which is angle bisector of the vertex angle is also the perpendicular bisector of the base.
So 7 = -17+2x
24= 2x
x=12
11. same with question 10, x= - 8 (7=x+15)
12. ×=11°
Please check the pic, m∠3 = m∠4 = （180°- 104°)/2=38°
m∠5=90°-m∠4=90°-38°=52°
m∠2=m∠5=52°
52°=4x+8° ×=11°