Abottle of detergent that will wash 32 loads of laundry costs $4.80. a bottle of detergent that will wash 50 loads of laundr costs $7.00. which one is the better deal?

I think the laundry detergent that costs $7.00 is better because if you buy two of them it will be $14.00 and it will wash 100 loads. But of you buy two of the $4.80 detergent, it will be $9.60 and it will only wash 64 loads so I think the other one is better because it can wash 36 loads more for only $4.40 more.
I hope this is right and it helps! :)