You bought 4 boxes of facial tissues for $3.79. which is a better buy? a: 6 for $5.75 b: 2 for $1.96 c: 3 for $2.79 d: 1 for $.97

First you see how much costs one box that you have already bought.
3,79/4=0,947

Then you see how much cost the other boxes
A: 5,75/6=0,958
B: 1,96/2=0,98
C:2,79/3=0,93
D: 0,97

So, here the smallest number is C. 0,93. So answer C is correct.