Hello :
<span>The circumference of the circle is 24π inches
</span>
<span>The length of the arc is (100/360)×24π = 20.93 inches
</span><span>(The complete circumference would cover 360°. Angle
ALB is 100°)<span> </span></span>
Supplementary angles measure 180°. Make an equation:

Subtract 28 to leave the variable in the parentheses alone:

Add the 2 x's together:

Your new equation is:

Divide both sides by 2 to leave the variable alone

The supplement measures 76°
The answer to your question is D.