Question 969494
{{{ 1 / 8 = x / 40 }}}
where {{{ x }}} = number of cans
{{{ x = 5 }}}
You have {{{ 8 }}} cans, so there are 
{{{ 3 }}} cans left
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If {{{ y }}} = number of dogs,
{{{ 1 / 6 = 3 / y }}}
{{{ y = 18 }}}
8 cans will feed 40 puppies and 18 dogs
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check:
{{{ 40/8 + 18/6 = 5 + 3 }}}
{{{ 5 + 3 = 8 }}}