The total cost of an item including sales tax is directly proportional to its price. if the total cost of a $25 item is $25.75, what is the total cost on a $60 item?

$61.80

The proportion can be written ...

... total cost/price = $25.75/$25.00 = item cost/$60.00

Multiplying by $60, we get ...

... item cost = $60.00×25.75/25 = $60.00×1.03

... item cost = $61.80

Total cost = $61.8

Step-by-step explanation:

We know that the total cost of an item (including the sales tax) is directly proportional to its price so we can write is as:

Total cost ∝ price

To change this proportionality into an equality, we need a constant so it will be:

Total cost = k * price

Finding k when total cost is $25.75 and price is $25:

25.75 = k * 25

k = 1.03

Finding the total cost when price $60:

Total cost = 1.03 * 60

Total cost = $61.8