其它
There are three whole number $A$, $B$, $C$. $A\times B=45$, $B\times C=50$. $A+B+C=$~\uline{~~~~~~~~~~}~. 
Overseas Competition->Knowledge Point->Number Theory Modules->Prime Factorization
$45=3\times 3\times 5$  $50=2\times 5\times 5$  Because $B$ is the factor both number contains, $B=5$  Thus, $A=9$, $C=10$. 