is 12 dollars : 7 cans a unit rate or ratio
The expression "12 dollars : 7 cans" can be considered both a unit rate and a ratio, depending on how it is interpreted.
1) If we interpret it as "12 dollars per 7 cans," then it represents a unit rate. In this case, the unit rate would be $12 for every 7 cans.
2) If we interpret it as a comparison between the quantities of 12 dollars and 7 cans, without specifying a rate or per, then it represents a ratio. In this case, the ratio would be 12:7.
So, the expression can be seen as both a unit rate and a ratio, depending on the context or interpretation.