Answer:
Step-by-step explanation:
You have an angle bisector in AD. That means the sides are in proportion to to BD and DC
It's much easier just to look at the proportion.
AB / BD = AC/DC
18 / (3x - 3) = 15/(x + 5) Cross multiply
18*(x + 5) = 15 (3x - 3) Remove the brackets
18x + 90 = 45x - 45 Switch the sides.
45x - 45 = 18x + 90 Subtract 18x from both sides
-18x -18x
27x - 45 = 90 Add 45 to both sides
+45 45
27x = 135
x = 5
But that's not the answer (even though it is correct). You want BD
BD = 3x - 3
BD = 3*5 - 3
BD = 15 - 3
BD = 12
