Hey there! I'm happy to help!
To find the area of a triangle you multiply the base by the height.
We see that our base is 5 units long because it stretches from -6 to -1 on the coordinate plane. Our height is 8 because the y value goes from 3 to -5.
To find the area of a triangle, you just multiply the base by the height then divide by 2.
5(8)=40
40/2=20
The area is 20 square units.
Have a wonderful day! :D