Question 326897
Let C be covered seats, U uncovered seats.
1.{{{C+U=1500}}}
.
.
{{{25C+15U=28500}}}
2.{{{5C+3U=5700}}}
Multiply eq.1 by -3 and add to eq. 2 to eliminate U.
{{{-3C-3U+5C+3U=-4500+5700}}}
{{{2C=1200}}}
{{{highlight(C=600)}}}
Then from above,
{{{600+U=1500}}}
{{{highlight(U=900)}}}