Question 1055122
{{{ 90 = k*30 }}}
{{{ k = 3 }}}
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Let {{{ x }}} = cubic ft of cement needed
{{{ 870 = k*x }}}
{{{ 870 = 3x }}}
{{{ x = 290 }}}
{{{ 290 - 30 = 260 }}}
260 additional ft3 of cement are needed