Respuesta :

We need some sort of diagram to see what they are. Is there any way to say that ac = db? Either equal angles or equal lines. 
x + 3 = 3x - 19 Add 19
x + 3 + 19 = 3x Subtract x
21 = 2x
x = 21 / 2
x = 10.5

ac = 10.5 + 3
x = 13.5