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Sally invested some money at 15 % interest. Sally also invested $172 more than 3 times that amount at
14%. How much is invested at each rate if Sally receives $1398.35 in interest after one year? (Round to
two decimal places if necessary.)

Respuesta :

adioabiola

Answer:

Amount at 15%=$2,411

Amount at 14%=$7,405

Step-by-step explanation:

let

x= the amount at 15% rate.

y=amount at 14% rate

y= x times 3 plus $172

y= 3x + $172 (1)

x times 15% plus y times 14% equals a return of $1,398.35 after one year

0.15x + 0.14y= $1,398.35 (2)

Recall,

y= 3x + $172

Substitute (1) into (2)

0.15x + 0.14y= $1,398.35

0.15x + 0.14(3x+172)=1398.35

0.15x + 0.42x + 24.08=1398.35

Collect like terms

0.15x + 0.42x=1398.35 - 24.08

0.57x=1374.27

Divide both sides by 0.57

x=2,411

x=$2,411

Find y

y= 3x + $172

=3(2,411) + 172

=7,233+172

=7,405

y=$7,405

Amount at 15%=$2,411

Amount at 14%=$7,405

Check:

$2,411*0.15=$361.65

$7,405*0.14=$1036.70

Total=$361.65 + $1036.70

=$1,398.35