Answer:
a. x = 12
b. x = 4
Step-by-step explanation:
a. RECTANGLE
ABCD is a rectangle, AC and BD are its diagonals.
Diagonals of a rectangle are congruent.
Therefore,
AC = BD
10x + 8 = 9x + 20
10x - 9x = 20 - 8
x = 12
b. RHOMBUS
Diagonal of a rectangle bisect opposite angles.
Therefore,
(5x + 3)° = (2x + 15)°
5x + 3 = 2x + 15
5x - 2x = 15 - 3
3x = 12
x = 12/3
x = 4
