Question

For a Supplementary angle, what is THE VALUE OF X in this problem: (4x + 40)degrees and 3x

Answer 1

A supplementary angle means two angles that equal 180°

 4x + 40 + 3x = 180

7x + 40 = 180
       -40     -40
     ----------------
7x = 140       140 ÷ 7 = 20

Answer 2

If you add it all together it will be 180 so to work it out you would do this...
7x+40=180
7x=140
x=20

hope this helps :)