Question

What is Best Buy out of 3 lbs for 1.89 or 5lbs for 2.49

Answer 1

1.89 / 3 = 0.63 per pound
2.49/ 5 = 0.498 per pound

answer 
5lbs for 2.49 is the best buy

Answer 2

Divide the price by pounds to get the price for one pound: 

1.89 / 3 = 0.63
2.49 / 5 ≈ 50

5 pounds for $2.49 is the better deal.