Maria looked at the sketch of a section of roof shown below.

A. A triangle has two congruent angles

B. An obtuse triangle has one obtuse angle and two acute angles.

C. The sum of the measures of the Angles of a triangle is 180.

D. the measure of an exterior angle equals the sum of the measures of its two remote interior angles

So every triangle has to have an equal of 180 because if you spread it out and take a triangle apart then you can make a straight line, basically you need to have two same angles and one different, like you have in the model. The X is 40 like the other one. Hope this helps you answer the question. (I can’t completely answer but I hope this helps you understand better!)

23,598 because  513 x 40 = ( 500 x 40 ) + ( 10 X 40 ) + ( 3 x 40 ) = 20 000 + 400 + 120 = 20,520 and another partial product is  513 x 6 = ( 500 x 6 ) + ( 10 x 6 ) + ( 3 x 6 ) = 3 000 + 60 + 18 = 3,078. so 20,520 + 3,078 = 23,598