Explanation:
Since a trapezoid has 4 sides, the sum of the angles is 360 degrees.
The sum of the bottom two angles is 82*2 = 164.
360-164 = 196.
Dividing that by 2, because the two angles should be equal, we have that Q and T are both 98 degrees.
Now, you could've done it a lot faster just by noticing that an isosceles anything is symmetrical across at least one line. Here, if you cut through the midpoints of QT and RS, the trapezoid is symmetrical on both sides.
So T = 180-82=98. To explain how I got this, if you cut through the midpoints, you'd get another trapezoid with 2 right angles. I attached a picture.