Respuesta :
15 = 3 - (z+6)
15 = 3 - z - 6
z = 3 - 6 - 15
z = -18
check:
15 = 3 - (z+6)
15 = 3 - (-18+6)
15 = 3 - (-12)
15 = 3 + 12
15 = 15 (true)
15 = 3 - z - 6
z = 3 - 6 - 15
z = -18
check:
15 = 3 - (z+6)
15 = 3 - (-18+6)
15 = 3 - (-12)
15 = 3 + 12
15 = 15 (true)
So, 15 = 3 - z - 6 / + z;
15 + z = 3 - 6 ;
15 + z = -3 / -15;
z = -18;
Check the solution: 3 - (-18 + 6 ) = 3 - (-12) = 3 + 12 = 15. Okay!