Which is more economical: purchasing the economy size of a detergent at 7 kilograms for $7.15 or purchasing the regular size at 870 grams for $.60? and by how much $ do you save by purchasing the more economical choice?

The regular size is more economical.  You save $2.322.

Step-by-step explanation:

Consider the provided information.

We need to find the more economical purchasing.

The economy size of a detergent at 7 kilograms for $7.15  

The regular size at 870 grams for $.60

This can be written as:

Divide both sides by 870.

Now multiply both sides by 7000.

(∴1000 gm = 1kg )

Hence the cost of 7 kg regular size detergent is $4.828

Thus, the regular size is more economical.

For 7 kg economy size of a detergent we need to pay $7.15

For 7 kg regular size  detergent we need to pay $4.828

$7.15-$4.828=$2.322

Hence, you save $2.322.