Respuesta :

The sum of complementary angles is 90 degrees, thus

3x + 6 + 3x + 18 = 90
=> 6x + 24 = 90
=> 6x = 90 - 24 = 66
=> x = 66 / 6 = 11

=> m<A = 3(11) + 6 = 33 + 6 = 39 degrees.