Question 1102539
x, students
y, adults
{{{x=y-72}}}


Account for tickets:
{{{ x+y=628}}}
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substitute.
{{{(y-72)+y=628}}}
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{{{y-72+y=628}}}
{{{2y=628+72}}}
{{{2y=700}}}
{{{highlight(y=350)}}}-------------adults
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{{{x=350-72}}}
{{{highlight(x=278)}}}-----------students