The efficiency of the first faucet is $\frac1{70}$ and that of the other two is $\frac3{70}$.  Thus, it takes $1\div (\frac1{70}+\frac3{70}\times2)=10$ minutes to fill the pool. 
Water from the first faucet fills the swimming pool in $70$ minutes. Water from each of the two other faucets fills the same swimming pool $3$ times faster. In how many minutes will the swimming pool be filled if all three faucets are opened? 
Options:
a: $$210$$ 
b: $$40$$ 
c: $$30$$ 
d: $$20$$ 
e: $$10$$ 