Question 364421
Let A be the number of adults, C children.
1.{{{A/C=7/4}}}
2.{{{A=15+C}}}
From eq. 1,
{{{4A=7C}}}
From eq. 2,
{{{4A=60+4C}}}
Substitute from eq. 1,
{{{7C=60+4C}}}
{{{3C=60}}}
{{{highlight(C=20)}}}
Then from eq. 2,
{{{A=15+20}}}
{{{highlight(A=35)}}}