<span>So you have composed two functions, 
</span><span>h(x)=sin(x) and g(x)=arctan(x)</span>
<span>→f=h∘g</span><span>
meaning
</span><span>f(x)=h(g(x))</span>
<span>g:R→<span>[<span>−1;1</span>]</span></span>
<span>h:R→[−<span>π2</span>;<span>π2</span>]</span><span>
And since
</span><span>[−1;1]∈R→f is defined ∀x∈R</span><span>
And since arctan(x) is strictly increasing and continuous in [-1;1] ,
</span><span>h(g(]−∞;∞[))=h([−1;1])=[arctan(−1);arctan(1)]</span><span>
Meaning
</span><span>f:R→[arctan(−1);arctan(1)]=[−<span>π4</span>;<span>π4</span>]</span><span>
so there's your domain</span>
        
             
        
        
        
Let Issac work for x hours, and Ruby works 8 hours more than of Issac, so Ruby work for  hours.
 hours.
And Svetlana worked four times of Ruby, therefore Svetlana worked for

And total hours they worked together is 136. That is

So Issac worked for 16 hours, Ruby worked for 24 hours and Svetlana worked for 24 times 4 equals 96 hours .
 
        
             
        
        
        
 In order to figure out what the answer is you would have to divide the number of feet it fell by the time. If you do 35.75 divided by 3.25 it would be 11. 
So the answer most likely would be 11
Please correct me if I am wrong
Have a great day!