Answer:
82
Step-by-step explanation:
When finding a triangle's missing angle, you first have to know that all of the angles add up to 180. Then, you add the other sides, and subtract that from 180 to get the missing angle. But in this case... Your missing two... but given one other angle. So, because a straight lines angle is 180, you would take 143 and subtract it from 180 to get the other side. There is also more steps... and sorry for not explaining further... but it would take a pretty long time...
180-143=37
A=37
37+61+_=180
37+61=98
180-98=82
The missing angle is 82 degrees