Find the measure of the exterior angle

The sum of angles of a triangle is 180º.
In this case the angles are:
(x+8)º
(4x)º
180º-(7x-16)º    (this is the measure of the interior angle.)

We have the following equation:
(x+8)+(4x)+180º-(7x-16)=180

We solve this equation:
x+8+4x+180º-7x+16=180
x+4x-7x=180-180-16-8
-2x=-24
x=-24/-2
x=12

The measure of the exterior angle
(7x-16)º=(7*12-16)=84-16=68º

the measure of the exterior angle is 68º.

The answer is 6 weeks