posted by 6th Grade Math on .
How do I know what number goes on top and what number goes on the bottom. For example
3 pounds for $1.89
YOu can do it each way:
Both are unit rates, one is lbs/dollar, the other is dollars/lb
rate1= 1.89/3= 93 cents/lb or
rate2= 3/1.89= 1lb/1.57
You use the one depending on the type of problem..
What is the cost of 34 lbs?
cost= rate*lbs= .93dollars/lb *34 lbs
What is the amount I can get for 53 dollars
amount= 1lb/1.58dollars * 53 dollars
So which rate? Examine both, and examine what you are looking for.
Money goes on top