Question 714248
For the investment @ 6%, he earned
{{{ .06*15000 = 900 }}}
He wants to earn $1250 total interest
{{{ 1250 - 900 = 350 }}}
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Let {{{ x }}} = the amount that he must invest @7% 
in order to earn $350
{{{ .07x = 350 }}}
{{{ x = 350 / .07 }}}
{{{ x= 5000 }}}
He must invest $5,000 @ 7%