#### Answer

$∠A = 59^{\circ}$

#### Work Step by Step

we know sum of all three angles of triangle is 180∘
$m∠A+m∠B+m∠C= 180^{\circ}$
$m\angle A+39^{\circ}+82^{\circ} =180^{\circ}$
$m\angle A+121^{\circ} =180^{\circ}$
$∠A = 180^{\circ}−121^{\circ}$
$∠A = 59^{\circ}$