The following figures are not drawn to scale but AB and CD are straight lines. Find x:

angle AOD + 170=180 (sum of angles on a straight line)

angle AOD=180-170

angle AOD=10

Angle BOC(4x)+ 170= 180 (sum of angles on a straight line )

angle BOC(4x) =180-170

4x=10

4x/4=10/4

x=2.5

a complex number is a number that can be expressed in the form a + bi, where a and b are real numbers, and i is a solution of the equation x2 = −1. because no real number satisfies this equation, i is called an imaginary number. has no real solution, since the square of a real number cannot be negative.