Question 1111273
a=adults
c=children

{{{system(a+c=360,c+100=a)}}} Substitute c+100 for a,

{{{c+(c+100)=360}}} {{{2c+100=360}}} {{{2c=260}}} {{{highlight(c=130)}}}

{{{a+130=360}}} {{{highlight(a=230)}}} Check: {{{130+230=360}}} and {{{230-130=100}}}