Answer:
[tex]\huge\boxed{\tt\:81^{\circ}}[/tex]
Step-by-step explanation:
Supplementary angles are angles that together sum up to 180°. So, here, if 1 angle is 99° then, we must subtract 180° from it to get its supplementary pair.
[tex]\sf \: 180^{\circ} - 99^{\circ} = supplementary \: angle\\\\\\\Longrightarrow \sf\:180^{\circ} - 99^{\circ} = \boxed{\tt\:81^{\circ}}[/tex]
So, the supplementary pair of 99° is 81°.
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Hope it helps!
[tex]\mathfrak{Lucazz}[/tex]