Question 1191542
C, the capacity filled for can, volume.


Amount alcohol before the removal and replacement, {{{0.7C}}}


Remove  7 L of the original volume,  {{{0.7(C-7)}}} liters of just alcohol


Replace with 7 L of pure alcohol,  {{{0.7(C-7)+7}}} liters alcohol.
This is contained within C liters of solution.


{{{highlight_green((0.7(C-7)+7)/C=0.875)}}}-------simplify, and solve for C.