Which is more economical: purchasing the economy size of a detergent at 3 kilograms for $3.15 or purchasing the regular size at 720 grams for 60c?

Due to the lower price per kilogram, purchasing the regular size at 720 grams for 60c is more economical.

Step-by-step explanation:

Which is more economical?

Whichever situation has the lowest price per kilogram.

3 kilograms for $3.15

3.15/3 = $1.05 per kilogram.

720 grams for 60c

0.6/0.72 = $0.83 per kilogram.

Due to the lower price per kilogram, purchasing the regular size at 720 grams for 60c is more economical.

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so: