A man realizes he lost the detailed receipt from the store and only has the credit card receipt with the after-tax total. If the after-tax total was $1,223.79, and the tax rate in the area is 8.3%, what was the pre-tax subtotal?

Answer: $1,130 is the pre-tax subtotal

Step-by-step explanation:

Let P the pre-tax subtotal.

The after-tax total = P + P·8,3/100 = P + 0,083P = P (1 + 0,083) = 1,083P

Since we know the after-tax total, we can substitute its value here:

1,083P = $1,223.79

P = $1,223.79/1,083 = $1,130, this is the pre-tax subtotal

Answer: $1,130 is the pre-tax subtotal

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