Answer: 36.04 dollars
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Explanation:
He gets a 15% discount, so he pays the remaining 85%. The two percentages add to 100%.
85% in decimal form is 0.85
The 6% sales tax means we also have the multiplier 1.06 to indicate a 6% increase.
The two factors 0.85 and 1.06 multiply to 0.85*1.06 = 0.901
This tells us that Andrew's father pays 90.1% of the original bill
0.901*40 = 36.04 dollars
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An alternative method:
15% of $40 = 0.15*40 = 6
Andrew's father saves $6
The bill of $40 drops to 40-6 = 34 dollars before tax.
6% of $34 = 0.06*34 = 2.04
The father pays $2.04 in tax to get a total bill of 34+2.04 = 36.04 dollars
