Answer:
β = (-0.19 dB).
Step-by-step explanation:
The formula which is used to calculate the decibel level of a sound is given by :

I is intensity of the sound of a ticking clock
watts per square meter
Since, 
The intensity of a monster truck is converted into per square meter as follows:

So, Decibal level is :

So, the decibel level of the sound of a ticking clock is (-0.19 dB).
X+y=4000....(1)
10x+6y=340*100⇒5x+3y=17000......(2)
(2)- 3*(1)⇒ 2x=5000⇒x=2500,y=4000-2500=1500