To find unit rate, you should identify your unit, in this case being pounds, and divide it by itself. Then, you should divide whatever it is being compared to by the same number.
4=3.88
/4 /4
1=0.97
3=3.06
/3 /3
1=1.02
Using the math above, we can see that 4 pounds for $3.88 is a better deal than 3 pounds for $3.06.
You could have also solved this by estimating. You can see that you can get 4 pounds for under 4 dollars, but 3 pounds is more than 3 dollars, meaning that the 4 for under 4 is a better deal.
