Help me find the missing angles

  b) 105°

  d) 130°

Step-by-step explanation:

An external angle has the same measure as the sum of the remote internal angles.

b) ? = 25° +80° = 105°

d) ? = 35° +95° = 130°

This should be fairly obvious if you consider that the adjacent internal angle together with the external angle totals 180°, and the adjacent internal angle together with the other two internal angles totals 180°.

If the two "remote" angles are A and B, and the adjacent internal angle is C, then we have in symbols ...

  A + B + C = 180° = ? + C

If we subtract C, then we find ...

  A + B = ? . . . . . . the fact we used above