Question 1045054
Let {{{ n }}} = the number of shirts Bob has to sell
{{{ 12n + ( n/10 )*5 + 50 = 1372 }}} 
( assuming he sells more than {{{ 100 }}} )
{{{ 12n + n/2 + 50 = 1372 }}}
{{{ 12n + n/2 = 1322 }}}
{{{ 24n + n = 2644 }}}
{{{ 25n = 2644 }}}
{{{ n = 105.76 }}}
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He will have to sell 106 shirts
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check the answer:
{{{ 12n + n/2 + 50 = 1372 }}}
{{{ 12*106 + 106/2 + 50 = 1372 }}} 
{{{ 1272 + 53 + 50 = 1372 }}}
{{{ 1272 + 103 = 1372 }}}
{{{ 1375 = 1372 }}}
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The left side is greater, so I'll try {{{ n = 105 }}}
{{{ 12*105 + 105/2 + 50 = 1372 }}}
{{{ 1260 + 52.5 + 50 = 1372 }}}
{{{ 1362.5 = 1372 }}}
the left side is smaller, so 106 shirts was correct
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You might want a 2nd opinion also