Question

Can anyone help with this

Answer 1

The sum of the interior angles of a triangle is always 180 degrees.  Thus,
the sum of 31, x+4 and 3x+9 must be 180.

31 + x + 4 + 3x + 9 = 180,     or    44 + 4x = 180


While it's not necessary, y ou could reduce this equation before solving for x:

11 + x = 45.             Then x = 34 degrees.

The three angles are then:

31
34+4 = 38
3(34) + 9 = 111

Check:  show that 31+38+111 = 180 (degrees)