document.write( "Question 1123865: Amelia is at looking at a sweater that costs $80. The store is having a 20% off sale and there is 8% sales tax Amelia is wondering which would cost less to take the 20% off then add the 8% tax or to add on the 8% sales tax then to take the 20% off. Help Amelia figure out which would cost less. \n" ); document.write( "
Algebra.Com's Answer #740240 by Theo(13342) You can put this solution on YOUR website! the sweater is on sale for $80.00\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "take the discount first and then pay the sales tax equals .8 * $80 * 1.07\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "pay the sales tax first and then take the discount equals $80 * 1.07 * .8\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "i think it will wind up being the same.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "breaking it down into more detail.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the price is $80.00 \n" ); document.write( "20% off is .2 * $80.00 = $16.00 \n" ); document.write( "$80.00 - $16.00 = $64 sale price \n" ); document.write( "7% sales tax on $64 = $4.48. \n" ); document.write( "$64 + $4.48 = $68.48 total\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the price is $80.00 \n" ); document.write( "7% sales tax on $80 = $5.60 \n" ); document.write( "$80.00 + $5.60 = $85.60 \n" ); document.write( "20% off is .2 * $85.60 = $17.12 \n" ); document.write( "$85.60 - $17.12 = $68.48 total\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the total price is the same.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "this has to do with the commutative law of multiplication that states that a * b is the same as b * a.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "20% discount is the same as multiplying the price by .8 \n" ); document.write( "7% sales tax is the same as multiplying the price by 1.07\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( ".8 * $80 * 1.07 is the same as 1.07 * $80 * .8\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the .8 factor is achieved in the following manner.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x - .2 * x = x * (1 - .2) = x * .8 = .8 * x\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the 1.07 factor is achieved in the following manner.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x + .07 * x = x * (1 + .07) = x * 1.07 = 1.07 * x\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |