Question 939697
Let the m^3 of silt in the soil they purchased = {{{ x }}}
Total amount of silt in their mix = {{{ 7 + x }}}
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{{{ ( 7 + x ) / ( 7 + 5 ) = .75 }}}
{{{ 7 + x = .75*12 }}}
{{{ 7 + x = 9 }}}
{{{ x = 2 }}}
There is 2 m^3 of silt in the 5 m^3 soil they purchased