Question 1098767
{{{ 12*15 = 180  }}} months total
{{{ 746*180 = 134280 }}} = interest plus
principal paid over 180 months
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{{{ i + P = 134280 }}}
{{{ I = 134280 - P }}}
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{{{ 134280 - P = P*( 1 + r/12 )^(12*15 ) }}}
{{{ 134280 - P = P*( 1 + .066/12 )^180 }}}
{{{ 134280 = P + P*1.0055^180 }}}
{{{ 132480 = P*( 1 + 2.68394 ) }}}
{{{ P = 132480/3.68394 }}}
{{{ P = 35961.5 }}}
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Principal + down payment = 
{{{ 35961.5 + 31248 = 67209.5 }}}
The selling price was $67,209.50
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In 15 yrs, they pay $134,280
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check the math and get
a 2nd opinion if needed