It is helpful to estimate quotients when the number is very big.
Answer:
The answer is 15
Step-by-step explanation:
You just have to multiply angle BC times angle AC to have the answer because angle AB is verticle to angle BD.
Can you send us a picture of the question please
Of means multiplication
So

And then simplify the numerator ad denominator
=

And simplify the numerator and denominator again
=

And we are finally left with the answer which is