Well, the measurement of an exterior and the corresponding interior angle have to equal 180°. So that means the exterior angle, let's call it "e", plus the interior angle, let's call it "i", have to equal 180°:
e + i = 180°
Well, you know the measurement of the exterior angle, so we can solve for i to find the interior angle:
160° + i = 180°
i = 180° - 160°
i = 20°
Now, we know this is a right triangle, so that means one angle is equal to 90°. All of the angles must add to equal 180° in a triangle, so we can solve for "x" to find the unknown angle with this equation:
Well first things first You just subtract 2008-1920 to see how much the year gap is between the increasing percentage of the value of the gem 2008-1920=88 Then we must multiply 120x88 120x88 gives us a value of $105,60 Hoped this helped