8 because 12-4=8. Im writing this part for the 20 characters
Answer:
Step-by-step explanation:
Commission = 15% of sales amount
The amount Tania earned is:
Answer with Step-by-step explanation:
a.

Taking both sides log

Using identity:

Using identity:


b.
We know that

Using identity

c.

Substitute the values then we get

By using 
Hence, 
3^2 + height^2 = 9^2
9 + height^2 = 81
height ^2 = 72
height = sqrt(72)