document.write( "Question 165486: Donna invested her $33,000 bonus and received a total of $970 in interest after one year. If part of the money returned 4% and the remainder 2.25%,
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document.write( "then how much did she invest at each rate?\r
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document.write( "I need some help I am not sure how to work this problem out. Thank you \n" );
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Algebra.Com's Answer #121976 by gonzo(654)![]() ![]() ![]() You can put this solution on YOUR website! B = bonus = 33000 \n" ); document.write( "BI = bonus interest = 970. \n" ); document.write( "X = amount of money invested at .04 interest rate. \n" ); document.write( "Y = amount of money invested at .0225 interest rate. \n" ); document.write( "----- \n" ); document.write( "(.04*X) + (.0225)*Y = 970 (equation 1) \n" ); document.write( "you have 1 equation with 2 unknowns so you can't solve directly. \n" ); document.write( "----- \n" ); document.write( "X + Y = 33000 (equation 2) \n" ); document.write( "subtract X from both sides of equation. \n" ); document.write( "Y = 33000 - X \n" ); document.write( "----- \n" ); document.write( "you can replace Y with (33000-X) in equation 1. \n" ); document.write( "it becomes: \n" ); document.write( "(.04*X) + (.0225)*(33000-X) = 970 \n" ); document.write( "now you have 1 equation with 1 unknown so you can solve for X directly. \n" ); document.write( "remove parentheses: \n" ); document.write( ".04*X + .0225*33000 - .0225*X = 970 \n" ); document.write( "perform indicated operations: \n" ); document.write( ".04*X + 742.5 - .0225*X = 970 \n" ); document.write( ".0175*X + 742.5 = 970 \n" ); document.write( "subtract 742.5 from both sides of equation. \n" ); document.write( ".0175*X = 970 - 742.5 = 227.5 \n" ); document.write( "divide both sides of equation by .0175. \n" ); document.write( "X = 13000. \n" ); document.write( "Y = 33000 - 13000 = 20000 \n" ); document.write( "----- \n" ); document.write( "she invested 13000 at .04 interest rate (4%) = 520 interest. \n" ); document.write( "she invested 20000 at .0225 interest rate (2.25%) = 450 interest. \n" ); document.write( "total interest = 970. \n" ); document.write( "----- \n" ); document.write( " |