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Bob bought three kinds of meat: pork, beef and chicken with the total cost of $152. The ratio of the weight of pork, beef and chicken is~$2:4:3$. The ratio of the price per pound of pork, beef and chicken is~$6:5:2$. What is the sum of the last digits of the cost of each kind in dollars? 
Overseas Competition->Knowledge Point->Calculation Modules->Ratios and Proportions
Let~$x,\textbackslash{} y\textbackslash{} and\textbackslash{} z$~be the weight of pork, beef and chicken, respectively.  ~$\textbackslash{} x:y:z=2:4:3$~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ (1)  The ratio of the price will be~$\left( 6x\right):\left( 5y\right):\left( 2z\right).$  The costs of pork, beef and chicken are~$A,B\textbackslash{} and\textbackslash{} C,$~respectively.  ~$A=\dfrac{6x}{6x+5y+2z}\times152$~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~(2)  From (1), we get:  ~$y=2x,\textbackslash{} and\textbackslash{} z=\dfrac{3}{2}x$~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~(3)  (2) becomes:~$A=\dfrac{6x}{6x+5\left( 2x\right)+2\times\dfrac{3}{2}x}\times152=\dfrac{6x}{19x}\times152=48$  Similarly,~$B=\dfrac{5y}{6x+5y+2z}\times152=\dfrac{5y}{19x}\times152=\dfrac{10x}{19x}\times152=80.$  And~$C=\dfrac{2z}{6x+5y+2z}\times152=\dfrac{2z}{19x}\times152=\dfrac{3x}{19x}\times152=24.$  Pork costs $48 per pound, beef costs $80, and chicken costs $24.  The sum of the last digits of the costs is 8+0+4=12. 