Given triangle abc proof ma equals 66 2/3 what is the answers for the blanks drag and put it in the box by the blank the sum of angles in triangles is equal to 180 degrees there for em a+ and b+ in c equal 180 degrees using the blank 5x + 90 + x + 10 equal 180 degrees to solve for x combined the terms to get 6x + 100 equal 180 degrees using the blank 6 x equal 80 then using the division property equality acts 13 1/3 to find the measure angle a the using substitution property to get ma equal 513 1/3 finally separate lies in the expression get ma equals 66 2/3 what is the proof