$45=3\times 3\times 5$  $50=2\times 5\times 5$  Because $B$ is the factor both number contains, $B=5$  Thus, $A=9$, $C=10$. 
There are three whole numbers $A$, $B$ and $C$ ($B
eq 1$). $A\times B=45$, $B\times C=50$. $A+B+C=$~\uline{~~~~~~~~~~}~. 
(A) $$20$$ 
(B) $$23$$ 
(C) $$24$$ 
(D) $$29$$ 